18315557 has 4 divisors (see below), whose sum is σ = 19724460. Its totient is φ = 16906656.

The previous prime is 18315553. The next prime is 18315593. The reversal of 18315557 is 75551381.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 4669921 + 13645636 = 2161^2 + 3694^2 .

It is not a de Polignac number, because 18315557 - 2² = 18315553 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 (18315551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 704432 + ... + 704457.

It is an arithmetic number, because the mean of its divisors is an integer number (4931115).

Almost surely, 2^18315557 is an apocalyptic number.

It is an amenable number.

18315557 is a deficient number, since it is larger than the sum of its proper divisors (1408903).

18315557 is a wasteful number, since it uses less digits than its factorization.

18315557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1408902.

The product of its digits is 21000, while the sum is 35.

The square root of 18315557 is about 4279.6678609444. The cubic root of 18315557 is about 263.5967452699.

The spelling of 18315557 in words is "eighteen million, three hundred fifteen thousand, five hundred fifty-seven".