21256012 has 6 divisors (see below), whose sum is σ = 37198028. Its totient is φ = 10628004.

The previous prime is 21255973. The next prime is 21256013. The reversal of 21256012 is 21065212.

It is a super-2 number, since 2×21256012² = 903636092288288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21256013) by changing a digit.

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 as a sum of consecutive naturals, namely, 2656998 + ... + 2657005.

Almost surely, 2^21256012 is an apocalyptic number.

It is an amenable number.

21256012 is a deficient number, since it is larger than the sum of its proper divisors (15942016).

21256012 is a wasteful number, since it uses less digits than its factorization.

21256012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5314007 (or 5314005 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21256012 is about 4610.4242754870. The cubic root of 21256012 is about 277.0090314927.

The spelling of 21256012 in words is "twenty-one million, two hundred fifty-six thousand, twelve".