91912561 has 4 divisors (see below), whose sum is σ = 98982772. Its totient is φ = 84842352.

The previous prime is 91912549. The next prime is 91912609. The reversal of 91912561 is 16521919.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11182336 + 80730225 = 3344^2 + 8985^2 .

It is a cyclic number.

It is not a de Polignac number, because 91912561 - 2¹¹ = 91910513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91912511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3535086 + ... + 3535111.

It is an arithmetic number, because the mean of its divisors is an integer number (24745693).

Almost surely, 2^91912561 is an apocalyptic number.

It is an amenable number.

91912561 is a deficient number, since it is larger than the sum of its proper divisors (7070211).

91912561 is a wasteful number, since it uses less digits than its factorization.

91912561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7070210.

The product of its digits is 4860, while the sum is 34.

The square root of 91912561 is about 9587.1038901224. The cubic root of 91912561 is about 451.2926797721.

The spelling of 91912561 in words is "ninety-one million, nine hundred twelve thousand, five hundred sixty-one".