91431720 has 64 divisors (see below), whose sum is σ = 304776000. Its totient is φ = 24381504.

The previous prime is 91431713. The next prime is 91431733. The reversal of 91431720 is 2713419.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 41250 + ... + 43409.

It is an arithmetic number, because the mean of its divisors is an integer number (4762125).

Almost surely, 2^91431720 is an apocalyptic number.

91431720 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

91431720 is an abundant number, since it is smaller than the sum of its proper divisors (213344280).

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

91431720 is a wasteful number, since it uses less digits than its factorization.

91431720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84679 (or 84669 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 91431720 is about 9561.9935159986. The cubic root of 91431720 is about 450.5043234729.

The spelling of 91431720 in words is "ninety-one million, four hundred thirty-one thousand, seven hundred twenty".