21256064 has 16 divisors (see below), whose sum is σ = 42346320. Its totient is φ = 10627968.

The previous prime is 21256057. The next prime is 21256087. The reversal of 21256064 is 46065212.

It is a tau number, because it is divible by the number of its divisors (16).

It is a super-3 number, since 3×21256064³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82904 + ... + 83159.

It is an arithmetic number, because the mean of its divisors is an integer number (2646645).

Almost surely, 2^21256064 is an apocalyptic number.

It is an amenable number.

21256064 is a deficient number, since it is larger than the sum of its proper divisors (21090256).

21256064 is an equidigital number, since it uses as much as digits as its factorization.

21256064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166077 (or 166065 counting only the distinct ones).

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

The square root of 21256064 is about 4610.4299148778. The cubic root of 21256064 is about 277.0092573811.

The spelling of 21256064 in words is "twenty-one million, two hundred fifty-six thousand, sixty-four".