18681899 has 2 divisors, whose sum is σ = 18681900. Its totient is φ = 18681898.

The previous prime is 18681863. The next prime is 18681907. The reversal of 18681899 is 99818681.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18681899 - 2⁸ = 18681643 is a prime.

It is not a weakly prime, because it can be changed into another prime (18621899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9340949 + 9340950.

It is an arithmetic number, because the mean of its divisors is an integer number (9340950).

Almost surely, 2^18681899 is an apocalyptic number.

18681899 is a deficient number, since it is larger than the sum of its proper divisors (1).

18681899 is an equidigital number, since it uses as much as digits as its factorization.

18681899 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 50.

The square root of 18681899 is about 4322.2562395120. The cubic root of 18681899 is about 265.3426160584.

The spelling of 18681899 in words is "eighteen million, six hundred eighty-one thousand, eight hundred ninety-nine".