90717991 has 16 divisors (see below), whose sum is σ = 113075200. Its totient is φ = 70862688.

The previous prime is 90717941. The next prime is 90718009. The reversal of 90717991 is 19971709.

It is not a de Polignac number, because 90717991 - 2⁷ = 90717863 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90717941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 880 + ... + 13498.

It is an arithmetic number, because the mean of its divisors is an integer number (7067200).

Almost surely, 2^90717991 is an apocalyptic number.

90717991 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

90717991 is a deficient number, since it is larger than the sum of its proper divisors (22357209).

90717991 is a wasteful number, since it uses less digits than its factorization.

90717991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12718.

The product of its (nonzero) digits is 35721, while the sum is 43.

The square root of 90717991 is about 9524.5992566617. The cubic root of 90717991 is about 449.3290263778.

The spelling of 90717991 in words is "ninety million, seven hundred seventeen thousand, nine hundred ninety-one".