18861820 has 12 divisors (see below), whose sum is σ = 39609864. Its totient is φ = 7544720.

The previous prime is 18861809. The next prime is 18861827. The reversal of 18861820 is 2816881.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18861827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 471526 + ... + 471565.

It is an arithmetic number, because the mean of its divisors is an integer number (3300822).

Almost surely, 2^18861820 is an apocalyptic number.

18861820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18861820 is an abundant number, since it is smaller than the sum of its proper divisors (20748044).

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

18861820 is a wasteful number, since it uses less digits than its factorization.

18861820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 943100 (or 943098 counting only the distinct ones).

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 18861820 is about 4343.0196868078. The cubic root of 18861820 is about 266.1917136035.

The spelling of 18861820 in words is "eighteen million, eight hundred sixty-one thousand, eight hundred twenty".