18109661 has 2 divisors, whose sum is σ = 18109662. Its totient is φ = 18109660.

The previous prime is 18109639. The next prime is 18109667. The reversal of 18109661 is 16690181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15452761 + 2656900 = 3931^2 + 1630^2 .

It is a cyclic number.

It is not a de Polignac number, because 18109661 - 2²² = 13915357 is a prime.

It is equal to p_1157864 and since 18109661 and 1157864 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18109667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9054830 + 9054831.

It is an arithmetic number, because the mean of its divisors is an integer number (9054831).

Almost surely, 2^18109661 is an apocalyptic number.

It is an amenable number.

18109661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18109661 is an equidigital number, since it uses as much as digits as its factorization.

18109661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 18109661 is about 4255.5447359886. The cubic root of 18109661 is about 262.6052717600.

The spelling of 18109661 in words is "eighteen million, one hundred nine thousand, six hundred sixty-one".