91681920 has 192 divisors, whose sum is σ = 345608640. Its totient is φ = 22210560.

The previous prime is 91681879. The next prime is 91681927. The reversal of 91681920 is 2918619.

It is a tau number, because it is divible by the number of its divisors (192).

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

It is not an unprimeable number, because it can be changed into a prime (91681927) 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 23 ways as a sum of consecutive naturals, for example, 62637 + ... + 64083.

It is an arithmetic number, because the mean of its divisors is an integer number (1800045).

Almost surely, 2^91681920 is an apocalyptic number.

91681920 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 91681920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (172804320).

91681920 is an abundant number, since it is smaller than the sum of its proper divisors (253926720).

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

91681920 is a wasteful number, since it uses less digits than its factorization.

91681920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1483 (or 1468 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The square root of 91681920 is about 9575.0676237821. The cubic root of 91681920 is about 450.9148794704.

The spelling of 91681920 in words is "ninety-one million, six hundred eighty-one thousand, nine hundred twenty".