21656258825 has 12 divisors (see below), whose sum is σ = 26858989248. Its totient is φ = 17321634000.

The previous prime is 21656258807. The next prime is 21656258837. The reversal of 21656258825 is 52885265612.

It is not a de Polignac number, because 21656258825 - 2¹⁰ = 21656257801 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 50900 + ... + 214250.

It is an arithmetic number, because the mean of its divisors is an integer number (2238249104).

Almost surely, 2^21656258825 is an apocalyptic number.

21656258825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21656258825 is a deficient number, since it is larger than the sum of its proper divisors (5202730423).

21656258825 is a wasteful number, since it uses less digits than its factorization.

21656258825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168664 (or 168659 counting only the distinct ones).

The product of its digits is 2304000, while the sum is 50.

The spelling of 21656258825 in words is "twenty-one billion, six hundred fifty-six million, two hundred fifty-eight thousand, eight hundred twenty-five".