643516637 has 2 divisors, whose sum is σ = 643516638. Its totient is φ = 643516636.

The previous prime is 643516579. The next prime is 643516649. The reversal of 643516637 is 736615346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 524684836 + 118831801 = 22906^2 + 10901^2 .

It is a cyclic number.

It is not a de Polignac number, because 643516637 - 2²⁰ = 642468061 is a prime.

It is a super-2 number, since 2×643516637² = 828227324191579538, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 643516594 and 643516603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643516667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321758318 + 321758319.

It is an arithmetic number, because the mean of its divisors is an integer number (321758319).

Almost surely, 2^643516637 is an apocalyptic number.

It is an amenable number.

643516637 is a deficient number, since it is larger than the sum of its proper divisors (1).

643516637 is an equidigital number, since it uses as much as digits as its factorization.

643516637 is an evil number, because the sum of its binary digits is even.

The product of its digits is 272160, while the sum is 41.

The square root of 643516637 is about 25367.6297079566. The cubic root of 643516637 is about 863.3494031418.

The spelling of 643516637 in words is "six hundred forty-three million, five hundred sixteen thousand, six hundred thirty-seven".