18121613 has 2 divisors, whose sum is σ = 18121614. Its totient is φ = 18121612.

The previous prime is 18121603. The next prime is 18121633. The reversal of 18121613 is 31612181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 9815689 + 8305924 = 3133^2 + 2882^2 .

It is a cyclic number.

It is not a de Polignac number, because 18121613 - 2¹⁴ = 18105229 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 (18121603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9060806 + 9060807.

It is an arithmetic number, because the mean of its divisors is an integer number (9060807).

Almost surely, 2^18121613 is an apocalyptic number.

It is an amenable number.

18121613 is a deficient number, since it is larger than the sum of its proper divisors (1).

18121613 is an equidigital number, since it uses as much as digits as its factorization.

18121613 is an evil number, because the sum of its binary digits is even.

The product of its digits is 288, while the sum is 23.

The square root of 18121613 is about 4256.9487899198. The cubic root of 18121613 is about 262.6630303965.

Adding to 18121613 its reverse (31612181), we get a palindrome (49733794).

The spelling of 18121613 in words is "eighteen million, one hundred twenty-one thousand, six hundred thirteen".