18011557 has 2 divisors, whose sum is σ = 18011558. Its totient is φ = 18011556.

The previous prime is 18011533. The next prime is 18011603. The reversal of 18011557 is 75511081.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17969121 + 42436 = 4239^2 + 206^2 .

It is a cyclic number.

It is not a de Polignac number, because 18011557 - 2¹⁹ = 17487269 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18011657) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9005778 + 9005779.

It is an arithmetic number, because the mean of its divisors is an integer number (9005779).

Almost surely, 2^18011557 is an apocalyptic number.

It is an amenable number.

18011557 is a deficient number, since it is larger than the sum of its proper divisors (1).

18011557 is an equidigital number, since it uses as much as digits as its factorization.

18011557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1400, while the sum is 28.

The square root of 18011557 is about 4244.0024740803. The cubic root of 18011557 is about 262.1302161402.

The spelling of 18011557 in words is "eighteen million, eleven thousand, five hundred fifty-seven".