21474181 has 8 divisors (see below), whose sum is σ = 22414680. Its totient is φ = 20547072.

The previous prime is 21474143. The next prime is 21474217. The reversal of 21474181 is 18147412.

21474181 is a nontrivial binomial coefficient, being equal to C(6554, 2).

It can be written as a sum of positive squares in 4 ways, for example, as 225 + 21473956 = 15^2 + 4634^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a 5-Lehmer number, since φ(21474181) divides (21474181-1)⁵.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21474181 is a prime.

It is a super-2 number, since 2×21474181² = 922280899241522, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21474121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1 + ... + 6553.

It is an arithmetic number, because the mean of its divisors is an integer number (2801835).

It is a Poulet number, since it divides 2^21474180-1.

Almost surely, 2^21474181 is an apocalyptic number.

21474181 is the 6553-rd triangular number and also the 3277-th hexagonal number.

21474181 is the 2185-th centered nonagonal number.

It is an amenable number.

21474181 is a deficient number, since it is larger than the sum of its proper divisors (940499).

21474181 is a wasteful number, since it uses less digits than its factorization.

21474181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6695.

The product of its digits is 1792, while the sum is 28.

The square root of 21474181 is about 4634.0242770188. The cubic root of 21474181 is about 277.9535358745.

It can be divided in two parts, 2147 and 4181, that added together give a triangular number (6328 = T₁₁₂).

The spelling of 21474181 in words is "twenty-one million, four hundred seventy-four thousand, one hundred eighty-one".