91640780 has 72 divisors (see below), whose sum is σ = 244245456. Its totient is φ = 28560000.

The previous prime is 91640779. The next prime is 91640789. The reversal of 91640780 is 8704619.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 91640780.

It is not an unprimeable number, because it can be changed into a prime (91640789) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6530 + ... + 15030.

It is an arithmetic number, because the mean of its divisors is an integer number (3392298).

Almost surely, 2^91640780 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 91640780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (122122728).

91640780 is an abundant number, since it is smaller than the sum of its proper divisors (152604676).

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

91640780 is a wasteful number, since it uses less digits than its factorization.

91640780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8535 (or 8526 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 91640780 is about 9572.9190950305. The cubic root of 91640780 is about 450.8474237366.

The spelling of 91640780 in words is "ninety-one million, six hundred forty thousand, seven hundred eighty".