21256709375 has 24 divisors (see below), whose sum is σ = 28984613616. Its totient is φ = 15459400000.

The previous prime is 21256709347. The next prime is 21256709387. The reversal of 21256709375 is 57390765212.

It is not a de Polignac number, because 21256709375 - 2⁸ = 21256709119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 274814 + ... + 343563.

It is an arithmetic number, because the mean of its divisors is an integer number (1207692234).

Almost surely, 2^21256709375 is an apocalyptic number.

21256709375 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21256709375 is a deficient number, since it is larger than the sum of its proper divisors (7727904241).

21256709375 is an frugal number, since it uses more digits than its factorization.

21256709375 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618413 (or 618393 counting only the distinct ones).

The product of its (nonzero) digits is 793800, while the sum is 47.

The spelling of 21256709375 in words is "twenty-one billion, two hundred fifty-six million, seven hundred nine thousand, three hundred seventy-five".