91561923 has 12 divisors (see below), whose sum is σ = 134498520. Its totient is φ = 60006336.

The previous prime is 91561913. The next prime is 91561991. The reversal of 91561923 is 32916519.

91561923 is a `hidden beast` number, since 9 + 1 + 561 + 92 + 3 = 666.

It is not a de Polignac number, because 91561923 - 2⁴ = 91561907 is a prime.

It is not an unprimeable number, because it can be changed into a prime (91561913) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 85686 + ... + 86747.

It is an arithmetic number, because the mean of its divisors is an integer number (11208210).

Almost surely, 2^91561923 is an apocalyptic number.

91561923 is a deficient number, since it is larger than the sum of its proper divisors (42936597).

91561923 is a wasteful number, since it uses less digits than its factorization.

91561923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172498 (or 172495 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 91561923 is about 9568.7994544770. The cubic root of 91561923 is about 450.7180683782.

The spelling of 91561923 in words is "ninety-one million, five hundred sixty-one thousand, nine hundred twenty-three".