18351997 has 4 divisors (see below), whose sum is σ = 18360736. Its totient is φ = 18343260.

The previous prime is 18351989. The next prime is 18352001. The reversal of 18351997 is 79915381.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 18351997 - 2³ = 18351989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18351947) 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, 898 + ... + 6124.

It is an arithmetic number, because the mean of its divisors is an integer number (4590184).

Almost surely, 2^18351997 is an apocalyptic number.

It is an amenable number.

18351997 is a deficient number, since it is larger than the sum of its proper divisors (8739).

18351997 is an equidigital number, since it uses as much as digits as its factorization.

18351997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8738.

The product of its digits is 68040, while the sum is 43.

The square root of 18351997 is about 4283.9230852106. The cubic root of 18351997 is about 263.7714437916.

The spelling of 18351997 in words is "eighteen million, three hundred fifty-one thousand, nine hundred ninety-seven".