643963690 has 16 divisors (see below), whose sum is σ = 1166078592. Its totient is φ = 256042384.

The previous prime is 643963667. The next prime is 643963699. The reversal of 643963690 is 96369346.

It is a super-2 number, since 2×643963690² = 829378468076832200, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 643963690.

It is not an unprimeable number, because it can be changed into a prime (643963699) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 191134 + ... + 194473.

It is an arithmetic number, because the mean of its divisors is an integer number (72879912).

Almost surely, 2^643963690 is an apocalyptic number.

643963690 is a deficient number, since it is larger than the sum of its proper divisors (522114902).

643963690 is a wasteful number, since it uses less digits than its factorization.

643963690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 385781.

The product of its (nonzero) digits is 629856, while the sum is 46.

The square root of 643963690 is about 25376.4396635935. The cubic root of 643963690 is about 863.5492806982.

It can be divided in two parts, 64396 and 3690, that added together give a palindrome (68086).

The spelling of 643963690 in words is "six hundred forty-three million, nine hundred sixty-three thousand, six hundred ninety".