18397665 has 64 divisors (see below), whose sum is σ = 38465280. Its totient is φ = 8225280.

The previous prime is 18397651. The next prime is 18397667. The reversal of 18397665 is 56679381.

It is a happy number.

It is not a de Polignac number, because 18397665 - 2⁴ = 18397649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 18397665.

It is not an unprimeable number, because it can be changed into a prime (18397667) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 18829 + ... + 19781.

It is an arithmetic number, because the mean of its divisors is an integer number (601020).

Almost surely, 2^18397665 is an apocalyptic number.

18397665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

18397665 is the 2145-th decagonal number.

It is an amenable number.

18397665 is an abundant number, since it is smaller than the sum of its proper divisors (20067615).

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

18397665 is a wasteful number, since it uses less digits than its factorization.

18397665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 991 (or 985 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 18397665 is about 4289.2499344291. The cubic root of 18397665 is about 263.9900564437.

It can be divided in two parts, 183976 and 65, that added together give a square (184041 = 429²).

The spelling of 18397665 in words is "eighteen million, three hundred ninety-seven thousand, six hundred sixty-five".