91399920 has 80 divisors (see below), whose sum is σ = 284377632. Its totient is φ = 24284160.

The previous prime is 91399901. The next prime is 91399949. The reversal of 91399920 is 2999319.

It is a happy number.

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

It is a congruent number.

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, 89010 + ... + 90030.

Almost surely, 2^91399920 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 91399920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142188816).

91399920 is an abundant number, since it is smaller than the sum of its proper divisors (192977712).

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

91399920 is a wasteful number, since it uses less digits than its factorization.

91399920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1410 (or 1404 counting only the distinct ones).

The product of its (nonzero) digits is 39366, while the sum is 42.

The square root of 91399920 is about 9560.3305382189. The cubic root of 91399920 is about 450.4520888703.

The spelling of 91399920 in words is "ninety-one million, three hundred ninety-nine thousand, nine hundred twenty".