18961961 has 2 divisors, whose sum is σ = 18961962. Its totient is φ = 18961960.

The previous prime is 18961949. The next prime is 18961993. The reversal of 18961961 is 16916981.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14784025 + 4177936 = 3845^2 + 2044^2 .

It is a cyclic number.

It is not a de Polignac number, because 18961961 - 2⁶ = 18961897 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18961561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9480980 + 9480981.

It is an arithmetic number, because the mean of its divisors is an integer number (9480981).

Almost surely, 2^18961961 is an apocalyptic number.

It is an amenable number.

18961961 is a deficient number, since it is larger than the sum of its proper divisors (1).

18961961 is an equidigital number, since it uses as much as digits as its factorization.

18961961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23328, while the sum is 41.

The square root of 18961961 is about 4354.5333848760. The cubic root of 18961961 is about 266.6619698826.

The spelling of 18961961 in words is "eighteen million, nine hundred sixty-one thousand, nine hundred sixty-one".