21413081 has 4 divisors (see below), whose sum is σ = 22672692. Its totient is φ = 20153472.

The previous prime is 21413053. The next prime is 21413083. The reversal of 21413081 is 18031412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15366400 + 6046681 = 3920^2 + 2459^2 .

It is a cyclic number.

It is not a de Polignac number, because 21413081 - 2¹⁸ = 21150937 is a prime.

It is a super-2 number, since 2×21413081² = 917040075825122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21413083) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 629780 + ... + 629813.

It is an arithmetic number, because the mean of its divisors is an integer number (5668173).

Almost surely, 2^21413081 is an apocalyptic number.

It is an amenable number.

21413081 is a deficient number, since it is larger than the sum of its proper divisors (1259611).

21413081 is a wasteful number, since it uses less digits than its factorization.

21413081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1259610.

The product of its (nonzero) digits is 192, while the sum is 20.

The square root of 21413081 is about 4627.4270388630. The cubic root of 21413081 is about 277.6896671596.

Adding to 21413081 its reverse (18031412), we get a palindrome (39444493).

The spelling of 21413081 in words is "twenty-one million, four hundred thirteen thousand, eighty-one".