18642539 has 2 divisors, whose sum is σ = 18642540. Its totient is φ = 18642538.

The previous prime is 18642517. The next prime is 18642583. The reversal of 18642539 is 93524681.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18642539 is a prime.

It is not a weakly prime, because it can be changed into another prime (18642509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9321269 + 9321270.

It is an arithmetic number, because the mean of its divisors is an integer number (9321270).

Almost surely, 2^18642539 is an apocalyptic number.

18642539 is a deficient number, since it is larger than the sum of its proper divisors (1).

18642539 is an equidigital number, since it uses as much as digits as its factorization.

18642539 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 38.

The square root of 18642539 is about 4317.7006612316. The cubic root of 18642539 is about 265.1561391458.

The spelling of 18642539 in words is "eighteen million, six hundred forty-two thousand, five hundred thirty-nine".