91728720 has 80 divisors (see below), whose sum is σ = 315961920. Its totient is φ = 24460416.

The previous prime is 91728701. The next prime is 91728727. The reversal of 91728720 is 2782719.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91728727) 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, 19074 + ... + 23393.

It is an arithmetic number, because the mean of its divisors is an integer number (3949524).

Almost surely, 2^91728720 is an apocalyptic number.

91728720 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

91728720 is an abundant number, since it is smaller than the sum of its proper divisors (224233200).

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

91728720 is a wasteful number, since it uses less digits than its factorization.

91728720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42489 (or 42477 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 91728720 is about 9577.5111589598. The cubic root of 91728720 is about 450.9915911661.

The spelling of 91728720 in words is "ninety-one million, seven hundred twenty-eight thousand, seven hundred twenty".