18813961 has 2 divisors, whose sum is σ = 18813962. Its totient is φ = 18813960.

The previous prime is 18813947. The next prime is 18813983. The reversal of 18813961 is 16931881.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10725625 + 8088336 = 3275^2 + 2844^2 .

It is a cyclic number.

It is not a de Polignac number, because 18813961 - 2⁹ = 18813449 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18813961.

It is not a weakly prime, because it can be changed into another prime (18813941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9406980 + 9406981.

It is an arithmetic number, because the mean of its divisors is an integer number (9406981).

Almost surely, 2^18813961 is an apocalyptic number.

It is an amenable number.

18813961 is a deficient number, since it is larger than the sum of its proper divisors (1).

18813961 is an equidigital number, since it uses as much as digits as its factorization.

18813961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 37.

The square root of 18813961 is about 4337.5063112346. The cubic root of 18813961 is about 265.9663825833.

The spelling of 18813961 in words is "eighteen million, eight hundred thirteen thousand, nine hundred sixty-one".