1321321961 has 2 divisors, whose sum is σ = 1321321962. Its totient is φ = 1321321960.

The previous prime is 1321321913. The next prime is 1321321987. The reversal of 1321321961 is 1691231231.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 970696336 + 350625625 = 31156^2 + 18725^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1321321961 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (1321321361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 660660980 + 660660981.

It is an arithmetic number, because the mean of its divisors is an integer number (660660981).

Almost surely, 2^1321321961 is an apocalyptic number.

It is an amenable number.

1321321961 is a deficient number, since it is larger than the sum of its proper divisors (1).

1321321961 is an equidigital number, since it uses as much as digits as its factorization.

1321321961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1944, while the sum is 29.

The square root of 1321321961 is about 36349.9925859690. The cubic root of 1321321961 is about 1097.3273852951.

The spelling of 1321321961 in words is "one billion, three hundred twenty-one million, three hundred twenty-one thousand, nine hundred sixty-one".