81673539408 has 40 divisors (see below), whose sum is σ = 234433308800. Its totient is φ = 27224512992.

The previous prime is 81673539383. The next prime is 81673539413. The reversal of 81673539408 is 80493537618.

81673539408 is a `hidden beast` number, since 8 + 1 + 67 + 3 + 539 + 40 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 94529128 + ... + 94529991.

It is an arithmetic number, because the mean of its divisors is an integer number (5860832720).

Almost surely, 2^81673539408 is an apocalyptic number.

It is an amenable number.

81673539408 is an abundant number, since it is smaller than the sum of its proper divisors (152759769392).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81673539408 is a wasteful number, since it uses less digits than its factorization.

81673539408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 189059136 (or 189059124 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 54.

The spelling of 81673539408 in words is "eighty-one billion, six hundred seventy-three million, five hundred thirty-nine thousand, four hundred eight".