18721700 has 18 divisors (see below), whose sum is σ = 40626306. Its totient is φ = 7488640.

The previous prime is 18721699. The next prime is 18721723. The reversal of 18721700 is 712781.

It can be written as a sum of positive squares in 3 ways, for example, as 2383936 + 16337764 = 1544^2 + 4042^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 18721700.

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 5 ways as a sum of consecutive naturals, for example, 93509 + ... + 93708.

It is an arithmetic number, because the mean of its divisors is an integer number (2257017).

Almost surely, 2^18721700 is an apocalyptic number.

18721700 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18721700 is an abundant number, since it is smaller than the sum of its proper divisors (21904606).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18721700 is a wasteful number, since it uses less digits than its factorization.

18721700 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 187231 (or 187224 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 26.

The square root of 18721700 is about 4326.8579824163. The cubic root of 18721700 is about 265.5309161606.

The spelling of 18721700 in words is "eighteen million, seven hundred twenty-one thousand, seven hundred".