91720512 has 140 divisors (see below), whose sum is σ = 293017956. Its totient is φ = 28200960.

The previous prime is 91720477. The next prime is 91720513. The reversal of 91720512 is 21502719.

It can be written as a sum of positive squares in 2 ways, for example, as 14561856 + 77158656 = 3816^2 + 8784^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91720513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 66712 + ... + 68072.

Almost surely, 2^91720512 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 91720512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146508978).

91720512 is an abundant number, since it is smaller than the sum of its proper divisors (201297444).

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

91720512 is a wasteful number, since it uses less digits than its factorization.

91720512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1398 (or 1379 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 91720512 is about 9577.0826455659. The cubic root of 91720512 is about 450.9781390020.

The spelling of 91720512 in words is "ninety-one million, seven hundred twenty thousand, five hundred twelve".