642735568 has 10 divisors (see below), whose sum is σ = 1245300194. Its totient is φ = 321367776.

The previous prime is 642735563. The next prime is 642735571. The reversal of 642735568 is 865537246.

It can be written as a sum of positive squares in only one way, i.e., 642723904 + 11664 = 25352^2 + 108^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (642735563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20085471 + ... + 20085502.

Almost surely, 2^642735568 is an apocalyptic number.

It is an amenable number.

642735568 is a deficient number, since it is larger than the sum of its proper divisors (602564626).

642735568 is a wasteful number, since it uses less digits than its factorization.

642735568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40170981 (or 40170975 counting only the distinct ones).

The product of its digits is 1209600, while the sum is 46.

The square root of 642735568 is about 25352.2300399787. The cubic root of 642735568 is about 862.9999646423. Note that the first 4 decimals are identical.

The spelling of 642735568 in words is "six hundred forty-two million, seven hundred thirty-five thousand, five hundred sixty-eight".