81537140887 has 4 divisors (see below), whose sum is σ = 81543164416. Its totient is φ = 81531117360.

The previous prime is 81537140849. The next prime is 81537140941. The reversal of 81537140887 is 78804173518.

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 81537140887 - 2²⁷ = 81402923159 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81537140387) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2991414 + ... + 3018547.

It is an arithmetic number, because the mean of its divisors is an integer number (20385791104).

Almost surely, 2^81537140887 is an apocalyptic number.

81537140887 is a deficient number, since it is larger than the sum of its proper divisors (6023529).

81537140887 is a wasteful number, since it uses less digits than its factorization.

81537140887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6023528.

The product of its (nonzero) digits is 1505280, while the sum is 52.

The spelling of 81537140887 in words is "eighty-one billion, five hundred thirty-seven million, one hundred forty thousand, eight hundred eighty-seven".