18720117 has 12 divisors (see below), whose sum is σ = 29120364. Its totient is φ = 11520000.

The previous prime is 18720083. The next prime is 18720173. The reversal of 18720117 is 71102781.

It can be written as a sum of positive squares in 2 ways, for example, as 12916836 + 5803281 = 3594^2 + 2409^2 .

It is not a de Polignac number, because 18720117 - 2²⁰ = 17671541 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18720197) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 79884 + ... + 80117.

It is an arithmetic number, because the mean of its divisors is an integer number (2426697).

Almost surely, 2^18720117 is an apocalyptic number.

It is an amenable number.

18720117 is a deficient number, since it is larger than the sum of its proper divisors (10400247).

18720117 is a wasteful number, since it uses less digits than its factorization.

18720117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160020 (or 160017 counting only the distinct ones).

The product of its (nonzero) digits is 784, while the sum is 27.

The square root of 18720117 is about 4326.6750513529. The cubic root of 18720117 is about 265.5234320239.

Adding to 18720117 its reverse (71102781), we get a palindrome (89822898).

The spelling of 18720117 in words is "eighteen million, seven hundred twenty thousand, one hundred seventeen".