18721870 has 16 divisors (see below), whose sum is σ = 33787008. Its totient is φ = 7469280.

The previous prime is 18721867. The next prime is 18721883. The reversal of 18721870 is 7812781.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 1987 + ... + 6433.

It is an arithmetic number, because the mean of its divisors is an integer number (2111688).

Almost surely, 2^18721870 is an apocalyptic number.

18721870 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

18721870 is a deficient number, since it is larger than the sum of its proper divisors (15065138).

18721870 is a wasteful number, since it uses less digits than its factorization.

18721870 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4875.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 18721870 is about 4326.8776271117. The cubic root of 18721870 is about 265.5317198647.

It can be divided in two parts, 18721 and 870, that added together give a palindrome (19591).

The spelling of 18721870 in words is "eighteen million, seven hundred twenty-one thousand, eight hundred seventy".