643402761 has 8 divisors (see below), whose sum is σ = 861430944. Its totient is φ = 427154880.

The previous prime is 643402741. The next prime is 643402763. The reversal of 643402761 is 167204346.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 643402761 - 2²⁵ = 609848329 is a prime.

It is a super-2 number, since 2×643402761² = 827934225724846242, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (643402763) 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, 444231 + ... + 445676.

It is an arithmetic number, because the mean of its divisors is an integer number (107678868).

Almost surely, 2^643402761 is an apocalyptic number.

It is an amenable number.

643402761 is a deficient number, since it is larger than the sum of its proper divisors (218028183).

643402761 is a wasteful number, since it uses less digits than its factorization.

643402761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 890151.

The product of its (nonzero) digits is 24192, while the sum is 33.

The square root of 643402761 is about 25365.3850946521. The cubic root of 643402761 is about 863.2984743490.

The spelling of 643402761 in words is "six hundred forty-three million, four hundred two thousand, seven hundred sixty-one".