18499661 has 2 divisors, whose sum is σ = 18499662. Its totient is φ = 18499660.

The previous prime is 18499643. The next prime is 18499693. The reversal of 18499661 is 16699481.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 1771561 = 4090^2 + 1331^2 .

It is an emirp because it is prime and its reverse (16699481) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18499661 is a prime.

It is a super-2 number, since 2×18499661² = 684474914229842, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18499601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9249830 + 9249831.

It is an arithmetic number, because the mean of its divisors is an integer number (9249831).

Almost surely, 2^18499661 is an apocalyptic number.

It is an amenable number.

18499661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18499661 is an equidigital number, since it uses as much as digits as its factorization.

18499661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312, while the sum is 44.

The square root of 18499661 is about 4301.1232253912. The cubic root of 18499661 is about 264.4770081608.

The spelling of 18499661 in words is "eighteen million, four hundred ninety-nine thousand, six hundred sixty-one".