18421720 has 16 divisors (see below), whose sum is σ = 41448960. Its totient is φ = 7368672.

The previous prime is 18421709. The next prime is 18421721. The reversal of 18421720 is 2712481.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18421721) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230232 + ... + 230311.

It is an arithmetic number, because the mean of its divisors is an integer number (2590560).

Almost surely, 2^18421720 is an apocalyptic number.

18421720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18421720 is an abundant number, since it is smaller than the sum of its proper divisors (23027240).

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

18421720 is a wasteful number, since it uses less digits than its factorization.

18421720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 460554 (or 460550 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 25.

The square root of 18421720 is about 4292.0531217589. The cubic root of 18421720 is about 264.1050622546.

It can be divided in two parts, 184 and 21720, that added together give a square (21904 = 148²).

The spelling of 18421720 in words is "eighteen million, four hundred twenty-one thousand, seven hundred twenty".