18981855 has 36 divisors (see below), whose sum is σ = 34867560. Its totient is φ = 9526464.

The previous prime is 18981847. The next prime is 18981871. The reversal of 18981855 is 55818981.

It is not a de Polignac number, because 18981855 - 2³ = 18981847 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 18981855.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 127321 + ... + 127469.

Almost surely, 2^18981855 is an apocalyptic number.

18981855 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

18981855 is a deficient number, since it is larger than the sum of its proper divisors (15885705).

18981855 is a wasteful number, since it uses less digits than its factorization.

18981855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328 (or 176 counting only the distinct ones).

The product of its digits is 115200, while the sum is 45.

The square root of 18981855 is about 4356.8170721296. The cubic root of 18981855 is about 266.7551936981.

The spelling of 18981855 in words is "eighteen million, nine hundred eighty-one thousand, eight hundred fifty-five".