91781979572465 has 32 divisors (see below), whose sum is σ = 135716491491840. Its totient is φ = 58025723940864.

The previous prime is 91781979572441. The next prime is 91781979572557. The reversal of 91781979572465 is 56427597918719.

It is a cyclic number.

It is not a de Polignac number, because 91781979572465 - 2¹⁶ = 91781979506929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91781979572465.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 119831984 + ... + 120595473.

It is an arithmetic number, because the mean of its divisors is an integer number (4241140359120).

Almost surely, 2^{91781979572465} is an apocalyptic number.

It is an amenable number.

91781979572465 is a deficient number, since it is larger than the sum of its proper divisors (43934511919375).

91781979572465 is a wasteful number, since it uses less digits than its factorization.

91781979572465 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 240428321.

The product of its digits is 2400451200, while the sum is 80.

The spelling of 91781979572465 in words is "ninety-one trillion, seven hundred eighty-one billion, nine hundred seventy-nine million, five hundred seventy-two thousand, four hundred sixty-five".