18315553 has 2 divisors, whose sum is σ = 18315554. Its totient is φ = 18315552.

The previous prime is 18315551. The next prime is 18315593. The reversal of 18315553 is 35551381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17875984 + 439569 = 4228^2 + 663^2 .

It is an emirp because it is prime and its reverse (35551381) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18315553 - 2¹ = 18315551 is a prime.

Together with 18315551, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18315551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9157776 + 9157777.

It is an arithmetic number, because the mean of its divisors is an integer number (9157777).

Almost surely, 2^18315553 is an apocalyptic number.

It is an amenable number.

18315553 is a deficient number, since it is larger than the sum of its proper divisors (1).

18315553 is an equidigital number, since it uses as much as digits as its factorization.

18315553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9000, while the sum is 31.

The square root of 18315553 is about 4279.6673936183. The cubic root of 18315553 is about 263.5967260806.

The spelling of 18315553 in words is "eighteen million, three hundred fifteen thousand, five hundred fifty-three".