81387755580251 has 4 divisors (see below), whose sum is σ = 81387941852400. Its totient is φ = 81387569308104.

The previous prime is 81387755580181. The next prime is 81387755580283. The reversal of 81387755580251 is 15208555778318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81387755580251 - 2¹⁰ = 81387755579227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81387755582251) 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 3 ways as a sum of consecutive naturals, for example, 92479136 + ... + 93355053.

It is an arithmetic number, because the mean of its divisors is an integer number (20346985463100).

Almost surely, 2^{81387755580251} is an apocalyptic number.

81387755580251 is a deficient number, since it is larger than the sum of its proper divisors (186272149).

81387755580251 is a wasteful number, since it uses less digits than its factorization.

81387755580251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186272148.

The product of its (nonzero) digits is 94080000, while the sum is 65.

The spelling of 81387755580251 in words is "eighty-one trillion, three hundred eighty-seven billion, seven hundred fifty-five million, five hundred eighty thousand, two hundred fifty-one".