18231557 has 4 divisors (see below), whose sum is σ = 18340896. Its totient is φ = 18122220.

The previous prime is 18231553. The next prime is 18231569. The reversal of 18231557 is 75513281.

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.

It is a cyclic number.

It is not a de Polignac number, because 18231557 - 2² = 18231553 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 (18231553) 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, 54419 + ... + 54752.

It is an arithmetic number, because the mean of its divisors is an integer number (4585224).

Almost surely, 2^18231557 is an apocalyptic number.

It is an amenable number.

18231557 is a deficient number, since it is larger than the sum of its proper divisors (109339).

18231557 is a wasteful number, since it uses less digits than its factorization.

18231557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109338.

The product of its digits is 8400, while the sum is 32.

The square root of 18231557 is about 4269.8427371509. The cubic root of 18231557 is about 263.1931527938.

The spelling of 18231557 in words is "eighteen million, two hundred thirty-one thousand, five hundred fifty-seven".