18879997 has 4 divisors (see below), whose sum is σ = 19161856. Its totient is φ = 18598140.

The previous prime is 18879919. The next prime is 18880007. The reversal of 18879997 is 79997881.

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 an emirpimes, since its reverse is a distinct semiprime: 79997881 = 449 ⋅178169.

It is a cyclic number.

It is not a de Polignac number, because 18879997 - 2⁷ = 18879869 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 (18879907) 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, 140829 + ... + 140962.

It is an arithmetic number, because the mean of its divisors is an integer number (4790464).

Almost surely, 2^18879997 is an apocalyptic number.

It is an amenable number.

18879997 is a deficient number, since it is larger than the sum of its proper divisors (281859).

18879997 is an equidigital number, since it uses as much as digits as its factorization.

18879997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281858.

The product of its digits is 2286144, while the sum is 58.

The square root of 18879997 is about 4345.1118512646. Note that the first 3 decimals coincide. The cubic root of 18879997 is about 266.2771951620.

The spelling of 18879997 in words is "eighteen million, eight hundred seventy-nine thousand, nine hundred ninety-seven".