25931571981 has 16 divisors (see below), whose sum is σ = 39606048384. Its totient is φ = 14783814144.

The previous prime is 25931571923. The next prime is 25931571983. The reversal of 25931571981 is 18917513952.

It is not a de Polignac number, because 25931571981 - 2⁶ = 25931571917 is a prime.

It is a super-5 number, since 5×25931571981⁵ (a number of 53 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25931571983) 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, 1416816 + ... + 1435001.

It is an arithmetic number, because the mean of its divisors is an integer number (2475378024).

Almost surely, 2^25931571981 is an apocalyptic number.

25931571981 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

25931571981 is a deficient number, since it is larger than the sum of its proper divisors (13674476403).

25931571981 is a wasteful number, since it uses less digits than its factorization.

25931571981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2852260.

The product of its digits is 680400, while the sum is 51.

The spelling of 25931571981 in words is "twenty-five billion, nine hundred thirty-one million, five hundred seventy-one thousand, nine hundred eighty-one".