91555993 has 8 divisors (see below), whose sum is σ = 94164840. Its totient is φ = 88965120.

The previous prime is 91555973. The next prime is 91556009. The reversal of 91555993 is 39955519.

It can be written as a sum of positive squares in 4 ways, for example, as 35485849 + 56070144 = 5957^2 + 7488^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 91555993 - 2⁹ = 91555481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91555903) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6193 + ... + 14881.

It is an arithmetic number, because the mean of its divisors is an integer number (11770605).

Almost surely, 2^91555993 is an apocalyptic number.

It is an amenable number.

91555993 is a deficient number, since it is larger than the sum of its proper divisors (2608847).

91555993 is a wasteful number, since it uses less digits than its factorization.

91555993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8987.

The product of its digits is 273375, while the sum is 46.

The square root of 91555993 is about 9568.4895882266. The cubic root of 91555993 is about 450.7083379293.

The spelling of 91555993 in words is "ninety-one million, five hundred fifty-five thousand, nine hundred ninety-three".