21256604 has 12 divisors (see below), whose sum is σ = 37901304. Its totient is φ = 10427664.

The previous prime is 21256597. The next prime is 21256633. The reversal of 21256604 is 40665212.

It is a super-2 number, since 2×21256604² = 903686427225632, which contains 22 as substring.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 49922 + ... + 50345.

It is an arithmetic number, because the mean of its divisors is an integer number (3158442).

Almost surely, 2^21256604 is an apocalyptic number.

It is an amenable number.

21256604 is a deficient number, since it is larger than the sum of its proper divisors (16644700).

21256604 is a wasteful number, since it uses less digits than its factorization.

21256604 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100324 (or 100322 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 26.

The square root of 21256604 is about 4610.4884773742. The cubic root of 21256604 is about 277.0116031232.

The spelling of 21256604 in words is "twenty-one million, two hundred fifty-six thousand, six hundred four".