81508578501 has 8 divisors (see below), whose sum is σ = 124203548224. Its totient is φ = 46576330560.

The previous prime is 81508578499. The next prime is 81508578509. The reversal of 81508578501 is 10587580518.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81508578501 - 2¹ = 81508578499 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81508578509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1940680420 + ... + 1940680461.

It is an arithmetic number, because the mean of its divisors is an integer number (15525443528).

Almost surely, 2^81508578501 is an apocalyptic number.

It is an amenable number.

81508578501 is a deficient number, since it is larger than the sum of its proper divisors (42694969723).

81508578501 is a wasteful number, since it uses less digits than its factorization.

81508578501 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3881360891.

The product of its (nonzero) digits is 448000, while the sum is 48.

The spelling of 81508578501 in words is "eighty-one billion, five hundred eight million, five hundred seventy-eight thousand, five hundred one".