25539720921 has 72 divisors (see below), whose sum is σ = 43678440000. Its totient is φ = 14255130240.

The previous prime is 25539720917. The next prime is 25539720971. The reversal of 25539720921 is 12902793552.

25539720921 is a `hidden beast` number, since 2 + 5 + 539 + 7 + 20 + 92 + 1 = 666.

It is not a de Polignac number, because 25539720921 - 2² = 25539720917 is a prime.

It is not an unprimeable number, because it can be changed into a prime (25539720901) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 8514580 + ... + 8517578.

It is an arithmetic number, because the mean of its divisors is an integer number (606645000).

Almost surely, 2^25539720921 is an apocalyptic number.

It is an amenable number.

25539720921 is a deficient number, since it is larger than the sum of its proper divisors (18138719079).

25539720921 is a wasteful number, since it uses less digits than its factorization.

25539720921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3551 (or 3535 counting only the distinct ones).

The product of its (nonzero) digits is 340200, while the sum is 45.

The spelling of 25539720921 in words is "twenty-five billion, five hundred thirty-nine million, seven hundred twenty thousand, nine hundred twenty-one".