643476961 has 2 divisors, whose sum is σ = 643476962. Its totient is φ = 643476960.

The previous prime is 643476941. The next prime is 643477007. The reversal of 643476961 is 169674346.

It is a happy number.

It is an a-pointer prime, because the next prime (643477007) can be obtained adding 643476961 to its sum of digits (46).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 457318225 + 186158736 = 21385^2 + 13644^2 .

It is a cyclic number.

It is not a de Polignac number, because 643476961 - 2⁵ = 643476929 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643476941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321738480 + 321738481.

It is an arithmetic number, because the mean of its divisors is an integer number (321738481).

Almost surely, 2^643476961 is an apocalyptic number.

It is an amenable number.

643476961 is a deficient number, since it is larger than the sum of its proper divisors (1).

643476961 is an equidigital number, since it uses as much as digits as its factorization.

643476961 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 46.

The square root of 643476961 is about 25366.8476756573. The cubic root of 643476961 is about 863.3316595162.

The spelling of 643476961 in words is "six hundred forty-three million, four hundred seventy-six thousand, nine hundred sixty-one".