643309637 has 2 divisors, whose sum is σ = 643309638. Its totient is φ = 643309636.

The previous prime is 643309577. The next prime is 643309643. The reversal of 643309637 is 736903346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 561026596 + 82283041 = 23686^2 + 9071^2 .

It is a cyclic number.

It is not a de Polignac number, because 643309637 - 2¹² = 643305541 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 643309594 and 643309603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643309687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321654818 + 321654819.

It is an arithmetic number, because the mean of its divisors is an integer number (321654819).

Almost surely, 2^643309637 is an apocalyptic number.

It is an amenable number.

643309637 is a deficient number, since it is larger than the sum of its proper divisors (1).

643309637 is an equidigital number, since it uses as much as digits as its factorization.

643309637 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 244944, while the sum is 41.

The square root of 643309637 is about 25363.5493770095. The cubic root of 643309637 is about 863.2568220119.

The spelling of 643309637 in words is "six hundred forty-three million, three hundred nine thousand, six hundred thirty-seven".