18556961 has 2 divisors, whose sum is σ = 18556962. Its totient is φ = 18556960.

The previous prime is 18556957. The next prime is 18556981. The reversal of 18556961 is 16965581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15649936 + 2907025 = 3956^2 + 1705^2 .

It is an emirp because it is prime and its reverse (16965581) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18556961 - 2² = 18556957 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18556921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9278480 + 9278481.

It is an arithmetic number, because the mean of its divisors is an integer number (9278481).

Almost surely, 2^18556961 is an apocalyptic number.

It is an amenable number.

18556961 is a deficient number, since it is larger than the sum of its proper divisors (1).

18556961 is an equidigital number, since it uses as much as digits as its factorization.

18556961 is an odious number, because the sum of its binary digits is odd.

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

The square root of 18556961 is about 4307.7791261856. The cubic root of 18556961 is about 264.7497863686.

The spelling of 18556961 in words is "eighteen million, five hundred fifty-six thousand, nine hundred sixty-one".