91631779857602 has 32 divisors (see below), whose sum is σ = 149467275304560. Its totient is φ = 41955092674560.

The previous prime is 91631779857587. The next prime is 91631779857623. The reversal of 91631779857602 is 20675897713619.

It is a Cunningham number, because it is equal to 9572449²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 81993369090361 + 9638410767241 = 9055019^2 + 3104579^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 279098102 + ... + 279426222.

Almost surely, 2^{91631779857602} is an apocalyptic number.

91631779857602 is a deficient number, since it is larger than the sum of its proper divisors (57835495446958).

91631779857602 is a wasteful number, since it uses less digits than its factorization.

91631779857602 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 550166.

The product of its (nonzero) digits is 240045120, while the sum is 71.

The spelling of 91631779857602 in words is "ninety-one trillion, six hundred thirty-one billion, seven hundred seventy-nine million, eight hundred fifty-seven thousand, six hundred two".