91661138 has 4 divisors (see below), whose sum is σ = 137491710. Its totient is φ = 45830568.

The previous prime is 91661051. The next prime is 91661147. The reversal of 91661138 is 83116619.

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

It can be written as a sum of positive squares in only one way, i.e., 90573289 + 1087849 = 9517^2 + 1043^2 .

It is a junction number, because it is equal to n+sod(n) for n = 91661098 and 91661107.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22915283 + ... + 22915286.

Almost surely, 2^91661138 is an apocalyptic number.

91661138 is a deficient number, since it is larger than the sum of its proper divisors (45830572).

91661138 is a wasteful number, since it uses less digits than its factorization.

91661138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45830571.

The product of its digits is 7776, while the sum is 35.

The square root of 91661138 is about 9573.9823480096. The cubic root of 91661138 is about 450.8808065177.

The spelling of 91661138 in words is "ninety-one million, six hundred sixty-one thousand, one hundred thirty-eight".