21475081 has 4 divisors (see below), whose sum is σ = 21494164. Its totient is φ = 21456000.

The previous prime is 21475079. The next prime is 21475127. The reversal of 21475081 is 18057412.

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 2509056 + 18966025 = 1584^2 + 4355^2 .

It is a cyclic number.

It is not a de Polignac number, because 21475081 - 2¹ = 21475079 is a prime.

It is a super-2 number, since 2×21475081² = 922358207913122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21475001) 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 3 ways as a sum of consecutive naturals, for example, 7740 + ... + 10141.

It is an arithmetic number, because the mean of its divisors is an integer number (5373541).

Almost surely, 2^21475081 is an apocalyptic number.

It is an amenable number.

21475081 is a deficient number, since it is larger than the sum of its proper divisors (19083).

21475081 is a wasteful number, since it uses less digits than its factorization.

21475081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19082.

The product of its (nonzero) digits is 2240, while the sum is 28.

The square root of 21475081 is about 4634.1213838224. The cubic root of 21475081 is about 277.9574189048.

The spelling of 21475081 in words is "twenty-one million, four hundred seventy-five thousand, eighty-one".