81637706880 has 96 divisors (see below), whose sum is σ = 281905226460. Its totient is φ = 21770053632.

The previous prime is 81637706869. The next prime is 81637706951. The reversal of 81637706880 is 8860773618.

It can be written as a sum of positive squares in 2 ways, for example, as 70471135296 + 11166571584 = 265464^2 + 105672^2 .

It is a tau number, because it is divible by the number of its divisors (96).

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7080847 + ... + 7092366.

Almost surely, 2^81637706880 is an apocalyptic number.

81637706880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81637706880 is an abundant number, since it is smaller than the sum of its proper divisors (200267519580).

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

81637706880 is a wasteful number, since it uses less digits than its factorization.

81637706880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14173238 (or 14173223 counting only the distinct ones).

The product of its (nonzero) digits is 2709504, while the sum is 54.

The spelling of 81637706880 in words is "eighty-one billion, six hundred thirty-seven million, seven hundred six thousand, eight hundred eighty".