17990991 has 56 divisors (see below), whose sum is σ = 29904480. Its totient is φ = 10777536.

The previous prime is 17990983. The next prime is 17991007. The reversal of 17990991 is 19909971.

It is not a de Polignac number, because 17990991 - 2³ = 17990983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17990941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 486225 + ... + 486261.

Almost surely, 2^17990991 is an apocalyptic number.

17990991 is a deficient number, since it is larger than the sum of its proper divisors (11913489).

17990991 is an equidigital number, since it uses as much as digits as its factorization.

17990991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 107 (or 92 counting only the distinct ones).

The product of its (nonzero) digits is 45927, while the sum is 45.

The square root of 17990991 is about 4241.5788334063. The cubic root of 17990991 is about 262.0304094222.

It can be divided in two parts, 17990 and 991, that added together give a palindrome (18981).

The spelling of 17990991 in words is "seventeen million, nine hundred ninety thousand, nine hundred ninety-one".