18172979 has 4 divisors (see below), whose sum is σ = 19825080. Its totient is φ = 16520880.

The previous prime is 18172901. The next prime is 18172993. The reversal of 18172979 is 97927181.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 97927181 = 11 ⋅8902471.

It is a cyclic number.

It is not a de Polignac number, because 18172979 - 2⁸ = 18172723 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18132979) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 826034 + ... + 826055.

It is an arithmetic number, because the mean of its divisors is an integer number (4956270).

Almost surely, 2^18172979 is an apocalyptic number.

18172979 is a deficient number, since it is larger than the sum of its proper divisors (1652101).

18172979 is a wasteful number, since it uses less digits than its factorization.

18172979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1652100.

The product of its digits is 63504, while the sum is 44.

The square root of 18172979 is about 4262.9777151658. The cubic root of 18172979 is about 262.9109704583.

The spelling of 18172979 in words is "eighteen million, one hundred seventy-two thousand, nine hundred seventy-nine".