21456591825 has 24 divisors (see below), whose sum is σ = 35500906368. Its totient is φ = 11435126080.

The previous prime is 21456591817. The next prime is 21456591829. The reversal of 21456591825 is 52819565412.

It is not a de Polignac number, because 21456591825 - 2³ = 21456591817 is a prime.

It is a hoax number, since the sum of its digits (48) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21456591829) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1209 + ... + 207158.

It is an arithmetic number, because the mean of its divisors is an integer number (1479204432).

Almost surely, 2^21456591825 is an apocalyptic number.

21456591825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21456591825 is a deficient number, since it is larger than the sum of its proper divisors (14044314543).

21456591825 is a wasteful number, since it uses less digits than its factorization.

21456591825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 209753 (or 209748 counting only the distinct ones).

The product of its digits is 864000, while the sum is 48.

The spelling of 21456591825 in words is "twenty-one billion, four hundred fifty-six million, five hundred ninety-one thousand, eight hundred twenty-five".