18891939 has 16 divisors (see below), whose sum is σ = 28151424. Its totient is φ = 11169600.

The previous prime is 18891919. The next prime is 18891953. The reversal of 18891939 is 93919881.

It is not a de Polignac number, because 18891939 - 2²⁰ = 17843363 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18891919) 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, 5629 + ... + 8334.

It is an arithmetic number, because the mean of its divisors is an integer number (1759464).

Almost surely, 2^18891939 is an apocalyptic number.

18891939 is a deficient number, since it is larger than the sum of its proper divisors (9259485).

18891939 is a wasteful number, since it uses less digits than its factorization.

18891939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14018.

The product of its digits is 139968, while the sum is 48.

The square root of 18891939 is about 4346.4858219026. The cubic root of 18891939 is about 266.3333253272. Note that the first 4 decimals are identical.

It can be divided in two parts, 1889 and 1939, that added together give a triangular number (3828 = T₈₇).

The spelling of 18891939 in words is "eighteen million, eight hundred ninety-one thousand, nine hundred thirty-nine".