91620720 has 140 divisors (see below), whose sum is σ = 319584456. Its totient is φ = 24416640.

The previous prime is 91620689. The next prime is 91620733. The reversal of 91620720 is 2702619.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 57535 + ... + 59105.

Almost surely, 2^91620720 is an apocalyptic number.

91620720 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91620720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (159792228).

91620720 is an abundant number, since it is smaller than the sum of its proper divisors (227963736).

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

91620720 is a wasteful number, since it uses less digits than its factorization.

91620720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1602 (or 1581 counting only the distinct ones).

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

The square root of 91620720 is about 9571.8712904008. The cubic root of 91620720 is about 450.8145247758.

The spelling of 91620720 in words is "ninety-one million, six hundred twenty thousand, seven hundred twenty".