643208831 has 4 divisors (see below), whose sum is σ = 644279664. Its totient is φ = 642138000.

The previous prime is 643208773. The next prime is 643208833. The reversal of 643208831 is 138802346.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643208831 is a prime.

It is a super-2 number, since 2×643208831² = 827435200552773122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643208791 and 643208800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643208833) 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, 534515 + ... + 535716.

It is an arithmetic number, because the mean of its divisors is an integer number (161069916).

Almost surely, 2^643208831 is an apocalyptic number.

643208831 is a deficient number, since it is larger than the sum of its proper divisors (1070833).

643208831 is a wasteful number, since it uses less digits than its factorization.

643208831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1070832.

The product of its (nonzero) digits is 27648, while the sum is 35.

The square root of 643208831 is about 25361.5620772854. The cubic root of 643208831 is about 863.2117291525.

The spelling of 643208831 in words is "six hundred forty-three million, two hundred eight thousand, eight hundred thirty-one".