91720560 has 80 divisors (see below), whose sum is σ = 285294240. Its totient is φ = 24376320.

The previous prime is 91720529. The next prime is 91720597. The reversal of 91720560 is 6502719.

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

It is a super-2 number, since 2×91720560² = 16825322253427200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

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, 110226 + ... + 111054.

It is an arithmetic number, because the mean of its divisors is an integer number (3566178).

Almost surely, 2^91720560 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 91720560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142647120).

91720560 is an abundant number, since it is smaller than the sum of its proper divisors (193573680).

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

91720560 is a wasteful number, since it uses less digits than its factorization.

91720560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1306 (or 1300 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 30.

The square root of 91720560 is about 9577.0851515479. The cubic root of 91720560 is about 450.9782176719.

The spelling of 91720560 in words is "ninety-one million, seven hundred twenty thousand, five hundred sixty".