21708774625 has 16 divisors (see below), whose sum is σ = 27142713936. Its totient is φ = 17334864000.

The previous prime is 21708774601. The next prime is 21708774629. The reversal of 21708774625 is 52647780712.

It can be written as a sum of positive squares in 8 ways, for example, as 4246737889 + 17462036736 = 65167^2 + 132144^2 .

It is not a de Polignac number, because 21708774625 - 2⁷ = 21708774497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21708774629) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 92884 + ... + 228133.

It is an arithmetic number, because the mean of its divisors is an integer number (1696419621).

Almost surely, 2^21708774625 is an apocalyptic number.

21708774625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21708774625 is a deficient number, since it is larger than the sum of its proper divisors (5433939311).

21708774625 is an equidigital number, since it uses as much as digits as its factorization.

21708774625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321573 (or 321563 counting only the distinct ones).

The product of its (nonzero) digits is 1317120, while the sum is 49.

The spelling of 21708774625 in words is "twenty-one billion, seven hundred eight million, seven hundred seventy-four thousand, six hundred twenty-five".