18955661 has 2 divisors, whose sum is σ = 18955662. Its totient is φ = 18955660.

The previous prime is 18955627. The next prime is 18955681. The reversal of 18955661 is 16655981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13734436 + 5221225 = 3706^2 + 2285^2 .

It is a cyclic number.

It is not a de Polignac number, because 18955661 - 2¹⁸ = 18693517 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18955681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9477830 + 9477831.

It is an arithmetic number, because the mean of its divisors is an integer number (9477831).

Almost surely, 2^18955661 is an apocalyptic number.

It is an amenable number.

18955661 is a deficient number, since it is larger than the sum of its proper divisors (1).

18955661 is an equidigital number, since it uses as much as digits as its factorization.

18955661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64800, while the sum is 41.

The square root of 18955661 is about 4353.8099407301. The cubic root of 18955661 is about 266.6324343210.

The spelling of 18955661 in words is "eighteen million, nine hundred fifty-five thousand, six hundred sixty-one".