81880509501 has 16 divisors (see below), whose sum is σ = 138633667200. Its totient is φ = 46788862464.

The previous prime is 81880509479. The next prime is 81880509511. The reversal of 81880509501 is 10590508818.

81880509501 is a `hidden beast` number, since 8 + 18 + 80 + 50 + 9 + 501 = 666.

It is not a de Polignac number, because 81880509501 - 2⁶ = 81880509437 is a prime.

It is a super-2 number, since 2×81880509501² (a number of 23 digits) contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81880509511) 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, 216614916 + ... + 216615293.

It is an arithmetic number, because the mean of its divisors is an integer number (8664604200).

Almost surely, 2^81880509501 is an apocalyptic number.

It is an amenable number.

81880509501 is a deficient number, since it is larger than the sum of its proper divisors (56753157699).

81880509501 is a wasteful number, since it uses less digits than its factorization.

81880509501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 433230225 (or 433230219 counting only the distinct ones).

The product of its (nonzero) digits is 115200, while the sum is 45.

The spelling of 81880509501 in words is "eighty-one billion, eight hundred eighty million, five hundred nine thousand, five hundred one".