25656387920 has 20 divisors (see below), whose sum is σ = 59651102100. Its totient is φ = 10262555136.

The previous prime is 25656387901. The next prime is 25656387931. The reversal of 25656387920 is 2978365652.

It can be written as a sum of positive squares in 2 ways, for example, as 19888896784 + 5767491136 = 141028^2 + 75944^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a super-2 number, since 2×25656387920² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 160352345 + ... + 160352504.

It is an arithmetic number, because the mean of its divisors is an integer number (2982555105).

Almost surely, 2^25656387920 is an apocalyptic number.

25656387920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

25656387920 is an abundant number, since it is smaller than the sum of its proper divisors (33994714180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

25656387920 is a wasteful number, since it uses less digits than its factorization.

25656387920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320704862 (or 320704856 counting only the distinct ones).

The product of its (nonzero) digits is 5443200, while the sum is 53.

The spelling of 25656387920 in words is "twenty-five billion, six hundred fifty-six million, three hundred eighty-seven thousand, nine hundred twenty".