91039978 has 4 divisors (see below), whose sum is σ = 136559970. Its totient is φ = 45519988.

The previous prime is 91039933. The next prime is 91039997. The reversal of 91039978 is 87993019.

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., 47651409 + 43388569 = 6903^2 + 6587^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 22759993 + ... + 22759996.

Almost surely, 2^91039978 is an apocalyptic number.

91039978 is a deficient number, since it is larger than the sum of its proper divisors (45519992).

91039978 is a wasteful number, since it uses less digits than its factorization.

91039978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45519991.

The product of its (nonzero) digits is 122472, while the sum is 46.

The square root of 91039978 is about 9541.4872006412. The cubic root of 91039978 is about 449.8600025411.

The spelling of 91039978 in words is "ninety-one million, thirty-nine thousand, nine hundred seventy-eight".