643857402 has 16 divisors (see below), whose sum is σ = 1297546272. Its totient is φ = 212980560.

The previous prime is 643857373. The next prime is 643857421. The reversal of 643857402 is 204758346.

It is a happy number.

It is a super-2 number, since 2×643857402² = 829104708220379208, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 408793 + ... + 410364.

It is an arithmetic number, because the mean of its divisors is an integer number (81096642).

Almost surely, 2^643857402 is an apocalyptic number.

643857402 is an abundant number, since it is smaller than the sum of its proper divisors (653688870).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

643857402 is a wasteful number, since it uses less digits than its factorization.

643857402 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 819293.

The product of its (nonzero) digits is 161280, while the sum is 39.

The square root of 643857402 is about 25374.3453511613. The cubic root of 643857402 is about 863.5017676797.

The spelling of 643857402 in words is "six hundred forty-three million, eight hundred fifty-seven thousand, four hundred two".