18405557 has 2 divisors, whose sum is σ = 18405558. Its totient is φ = 18405556.

The previous prime is 18405551. The next prime is 18405587. The reversal of 18405557 is 75550481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15928081 + 2477476 = 3991^2 + 1574^2 .

It is a cyclic number.

It is not a de Polignac number, because 18405557 - 2⁸ = 18405301 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 (18405551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9202778 + 9202779.

It is an arithmetic number, because the mean of its divisors is an integer number (9202779).

Almost surely, 2^18405557 is an apocalyptic number.

It is an amenable number.

18405557 is a deficient number, since it is larger than the sum of its proper divisors (1).

18405557 is an equidigital number, since it uses as much as digits as its factorization.

18405557 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 28000, while the sum is 35.

The square root of 18405557 is about 4290.1698101590. The cubic root of 18405557 is about 264.0277987639.

The spelling of 18405557 in words is "eighteen million, four hundred five thousand, five hundred fifty-seven".