91871138172 has 48 divisors (see below), whose sum is σ = 234591622272. Its totient is φ = 27751903680.

The previous prime is 91871138167. The next prime is 91871138173. The reversal of 91871138172 is 27183117819.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91871138173) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1055938 + ... + 1139625.

It is an arithmetic number, because the mean of its divisors is an integer number (4887325464).

Almost surely, 2^91871138172 is an apocalyptic number.

It is an amenable number.

91871138172 is an abundant number, since it is smaller than the sum of its proper divisors (142720484100).

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

91871138172 is a wasteful number, since it uses less digits than its factorization.

91871138172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2195898 (or 2195896 counting only the distinct ones).

The product of its digits is 169344, while the sum is 48.

The spelling of 91871138172 in words is "ninety-one billion, eight hundred seventy-one million, one hundred thirty-eight thousand, one hundred seventy-two".