643799690 has 16 divisors (see below), whose sum is σ = 1227006792. Its totient is φ = 242371584.

The previous prime is 643799687. The next prime is 643799701. The reversal of 643799690 is 96997346.

It can be written as a sum of positive squares in 4 ways, for example, as 643180321 + 619369 = 25361^2 + 787^2 .

It is a super-2 number, since 2×643799690² = 828956081688192200, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1893359 + ... + 1893698.

Almost surely, 2^643799690 is an apocalyptic number.

643799690 is a deficient number, since it is larger than the sum of its proper divisors (583207102).

643799690 is a wasteful number, since it uses less digits than its factorization.

643799690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3787081.

The product of its (nonzero) digits is 2204496, while the sum is 53.

The square root of 643799690 is about 25373.2081140718. The cubic root of 643799690 is about 863.4759669859.

The spelling of 643799690 in words is "six hundred forty-three million, seven hundred ninety-nine thousand, six hundred ninety".