18003720 has 64 divisors (see below), whose sum is σ = 61729920. Its totient is φ = 4114944.

The previous prime is 18003703. The next prime is 18003737. The reversal of 18003720 is 2730081.

It is an interprime number because it is at equal distance from previous prime (18003703) and next prime (18003737).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9877 + ... + 11556.

It is an arithmetic number, because the mean of its divisors is an integer number (964530).

Almost surely, 2^18003720 is an apocalyptic number.

18003720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18003720 is an abundant number, since it is smaller than the sum of its proper divisors (43726200).

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

18003720 is a wasteful number, since it uses less digits than its factorization.

18003720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21454 (or 21450 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 18003720 is about 4243.0790706750. The cubic root of 18003720 is about 262.0921921736.

The spelling of 18003720 in words is "eighteen million, three thousand, seven hundred twenty".