643634770 has 16 divisors (see below), whose sum is σ = 1170488088. Its totient is φ = 254799360.

The previous prime is 643634767. The next prime is 643634777. The reversal of 643634770 is 77436346.

It can be written as a sum of positive squares in 4 ways, for example, as 388050601 + 255584169 = 19699^2 + 15987^2 .

It is not an unprimeable number, because it can be changed into a prime (643634777) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 330801 + ... + 332740.

Almost surely, 2^643634770 is an apocalyptic number.

643634770 is a deficient number, since it is larger than the sum of its proper divisors (526853318).

643634770 is a wasteful number, since it uses less digits than its factorization.

643634770 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 663645.

The product of its (nonzero) digits is 254016, while the sum is 40.

The square root of 643634770 is about 25369.9580212503. The cubic root of 643634770 is about 863.4022294449.

The spelling of 643634770 in words is "six hundred forty-three million, six hundred thirty-four thousand, seven hundred seventy".