25661508816420 has 144 divisors (see below), whose sum is σ = 84971442104640. Its totient is φ = 6482907467136.

The previous prime is 25661508816397. The next prime is 25661508816457. The reversal of 25661508816420 is 2461880516652.

25661508816420 is a `hidden beast` number, since 2 + 5 + 6 + 615 + 0 + 8 + 8 + 16 + 4 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 138858867 + ... + 139043546.

It is an arithmetic number, because the mean of its divisors is an integer number (590079459060).

Almost surely, 2^{25661508816420} is an apocalyptic number.

25661508816420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

25661508816420 is an abundant number, since it is smaller than the sum of its proper divisors (59309933288220).

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

25661508816420 is a wasteful number, since it uses less digits than its factorization.

25661508816420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277902456 (or 277902442 counting only the distinct ones).

The product of its (nonzero) digits is 5529600, while the sum is 54.

The spelling of 25661508816420 in words is "twenty-five trillion, six hundred sixty-one billion, five hundred eight million, eight hundred sixteen thousand, four hundred twenty".