643168961 has 2 divisors, whose sum is σ = 643168962. Its totient is φ = 643168960.

The previous prime is 643168957. The next prime is 643169069. The reversal of 643168961 is 169861346.

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., 533841025 + 109327936 = 23105^2 + 10456^2 .

It is a cyclic number.

It is not a de Polignac number, because 643168961 - 2² = 643168957 is a prime.

It is not a weakly prime, because it can be changed into another prime (643168921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321584480 + 321584481.

It is an arithmetic number, because the mean of its divisors is an integer number (321584481).

Almost surely, 2^643168961 is an apocalyptic number.

It is an amenable number.

643168961 is a deficient number, since it is larger than the sum of its proper divisors (1).

643168961 is an equidigital number, since it uses as much as digits as its factorization.

643168961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 186624, while the sum is 44.

The square root of 643168961 is about 25360.7760330791. The cubic root of 643168961 is about 863.1938930776.

The spelling of 643168961 in words is "six hundred forty-three million, one hundred sixty-eight thousand, nine hundred sixty-one".