18791661 has 16 divisors (see below), whose sum is σ = 28905984. Its totient is φ = 10636464.

The previous prime is 18791659. The next prime is 18791687. The reversal of 18791661 is 16619781.

It is not a de Polignac number, because 18791661 - 2¹ = 18791659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18791761) 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, 1935 + ... + 6428.

It is an arithmetic number, because the mean of its divisors is an integer number (1806624).

Almost surely, 2^18791661 is an apocalyptic number.

It is an amenable number.

18791661 is a deficient number, since it is larger than the sum of its proper divisors (10114323).

18791661 is a wasteful number, since it uses less digits than its factorization.

18791661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8480.

The product of its digits is 18144, while the sum is 39.

The square root of 18791661 is about 4334.9349476088. The cubic root of 18791661 is about 265.8612586062.

The spelling of 18791661 in words is "eighteen million, seven hundred ninety-one thousand, six hundred sixty-one".