25981893721 has 9 divisors (see below), whose sum is σ = 30225148149. Its totient is φ = 22269227484.

The previous prime is 25981893697. The next prime is 25981893731. The reversal of 25981893721 is 12739818952.

It is a happy number.

The square root of 25981893721 is 161189.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 25981893721 - 2⁵ = 25981893689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (25981893731) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1116810 + ... + 1139836.

Almost surely, 2^25981893721 is an apocalyptic number.

25981893721 is the 161189-th square number.

25981893721 is the 80595-th centered octagonal number.

It is an amenable number.

25981893721 is a deficient number, since it is larger than the sum of its proper divisors (4243254428).

25981893721 is an frugal number, since it uses more digits than its factorization.

25981893721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46068 (or 23034 counting only the distinct ones).

The product of its digits is 2177280, while the sum is 55.

The spelling of 25981893721 in words is "twenty-five billion, nine hundred eighty-one million, eight hundred ninety-three thousand, seven hundred twenty-one".