18631649 has 2 divisors, whose sum is σ = 18631650. Its totient is φ = 18631648.

The previous prime is 18631637. The next prime is 18631667. The reversal of 18631649 is 94613681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15366400 + 3265249 = 3920^2 + 1807^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18631649 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (18631049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9315824 + 9315825.

It is an arithmetic number, because the mean of its divisors is an integer number (9315825).

Almost surely, 2^18631649 is an apocalyptic number.

It is an amenable number.

18631649 is a deficient number, since it is larger than the sum of its proper divisors (1).

18631649 is an equidigital number, since it uses as much as digits as its factorization.

18631649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 38.

The square root of 18631649 is about 4316.4393891262. The cubic root of 18631649 is about 265.1044989554.

The spelling of 18631649 in words is "eighteen million, six hundred thirty-one thousand, six hundred forty-nine".