643264751 has 4 divisors (see below), whose sum is σ = 681103872. Its totient is φ = 605425632.

The previous prime is 643264733. The next prime is 643264771. The reversal of 643264751 is 157462346.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 157462346 = 2 ⋅78731173.

It is a cyclic number.

It is not a de Polignac number, because 643264751 - 2²⁶ = 576155887 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643264711) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18919535 + ... + 18919568.

It is an arithmetic number, because the mean of its divisors is an integer number (170275968).

Almost surely, 2^643264751 is an apocalyptic number.

643264751 is a deficient number, since it is larger than the sum of its proper divisors (37839121).

643264751 is a wasteful number, since it uses less digits than its factorization.

643264751 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37839120.

The product of its digits is 120960, while the sum is 38.

The square root of 643264751 is about 25362.6645090771. The cubic root of 643264751 is about 863.2367440460.

The spelling of 643264751 in words is "six hundred forty-three million, two hundred sixty-four thousand, seven hundred fifty-one".