18307972 has 6 divisors (see below), whose sum is σ = 32038958. Its totient is φ = 9153984.

The previous prime is 18307937. The next prime is 18307979. The reversal of 18307972 is 27970381.

It can be written as a sum of positive squares in only one way, i.e., 16924996 + 1382976 = 4114^2 + 1176^2 .

It is not an unprimeable number, because it can be changed into a prime (18307979) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2288493 + ... + 2288500.

Almost surely, 2^18307972 is an apocalyptic number.

It is an amenable number.

18307972 is a deficient number, since it is larger than the sum of its proper divisors (13730986).

18307972 is a wasteful number, since it uses less digits than its factorization.

18307972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4576997 (or 4576995 counting only the distinct ones).

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 18307972 is about 4278.7816022789. The cubic root of 18307972 is about 263.5603525760.

The spelling of 18307972 in words is "eighteen million, three hundred seven thousand, nine hundred seventy-two".