25501636881 has 144 divisors (see below), whose sum is σ = 45653484240. Its totient is φ = 13655900160.

The previous prime is 25501636841. The next prime is 25501636891. The reversal of 25501636881 is 18863610552.

25501636881 is a `hidden beast` number, since 2 + 5 + 5 + 0 + 1 + 636 + 8 + 8 + 1 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 4529963025 + 20971673856 = 67305^2 + 144816^2 .

It is not a de Polignac number, because 25501636881 - 2¹⁴ = 25501620497 is a prime.

It is a super-2 number, since 2×25501636881² (a number of 22 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (25501636841) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 75672345 + ... + 75672681.

It is an arithmetic number, because the mean of its divisors is an integer number (317038085).

Almost surely, 2^25501636881 is an apocalyptic number.

25501636881 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

25501636881 is a deficient number, since it is larger than the sum of its proper divisors (20151847359).

25501636881 is a wasteful number, since it uses less digits than its factorization.

25501636881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 544 (or 534 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The spelling of 25501636881 in words is "twenty-five billion, five hundred one million, six hundred thirty-six thousand, eight hundred eighty-one".