18710991 has 36 divisors (see below), whose sum is σ = 30787848. Its totient is φ = 10883808.

The previous prime is 18710981. The next prime is 18711001. The reversal of 18710991 is 19901781.

It is an interprime number because it is at equal distance from previous prime (18710981) and next prime (18711001).

It is not a de Polignac number, because 18710991 - 2⁵ = 18710959 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18710911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 42016 + ... + 42458.

It is an arithmetic number, because the mean of its divisors is an integer number (855218).

Almost surely, 2^18710991 is an apocalyptic number.

18710991 is a deficient number, since it is larger than the sum of its proper divisors (12076857).

18710991 is a wasteful number, since it uses less digits than its factorization.

18710991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 500 (or 478 counting only the distinct ones).

The product of its (nonzero) digits is 4536, while the sum is 36.

The square root of 18710991 is about 4325.6203023382. The cubic root of 18710991 is about 265.4802777225.

It can be divided in two parts, 18710 and 991, that added together give a triangular number (19701 = T₁₉₈).

The spelling of 18710991 in words is "eighteen million, seven hundred ten thousand, nine hundred ninety-one".