18979997 has 4 divisors (see below), whose sum is σ = 18988896. Its totient is φ = 18971100.

The previous prime is 18979957. The next prime is 18979999. The reversal of 18979997 is 79997981.

It is a happy number.

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 18979997 - 2¹⁶ = 18914461 is a prime.

It is a super-2 number, since 2×18979997² = 720480572240018, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18979999) 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, 872 + ... + 6222.

It is an arithmetic number, because the mean of its divisors is an integer number (4747224).

Almost surely, 2^18979997 is an apocalyptic number.

It is an amenable number.

18979997 is a deficient number, since it is larger than the sum of its proper divisors (8899).

18979997 is an equidigital number, since it uses as much as digits as its factorization.

18979997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8898.

The product of its digits is 2571912, while the sum is 59.

The square root of 18979997 is about 4356.6038378535. The cubic root of 18979997 is about 266.7464898189.

The spelling of 18979997 in words is "eighteen million, nine hundred seventy-nine thousand, nine hundred ninety-seven".