21256995123 has 108 divisors (see below), whose sum is σ = 40600018368. Its totient is φ = 10621316160.

The previous prime is 21256995107. The next prime is 21256995167. The reversal of 21256995123 is 32159965212.

21256995123 is a `hidden beast` number, since 2 + 12 + 569 + 9 + 51 + 23 = 666.

It is not a de Polignac number, because 21256995123 - 2⁴ = 21256995107 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21256995173) 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 107 ways as a sum of consecutive naturals, for example, 2064478 + ... + 2074748.

It is an arithmetic number, because the mean of its divisors is an integer number (375926096).

Almost surely, 2^21256995123 is an apocalyptic number.

21256995123 is a deficient number, since it is larger than the sum of its proper divisors (19343023245).

21256995123 is a wasteful number, since it uses less digits than its factorization.

21256995123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10342 (or 10313 counting only the distinct ones).

The product of its digits is 291600, while the sum is 45.

The spelling of 21256995123 in words is "twenty-one billion, two hundred fifty-six million, nine hundred ninety-five thousand, one hundred twenty-three".