646655643 has 20 divisors (see below), whose sum is σ = 966790000. Its totient is φ = 430747632.

The previous prime is 646655621. The next prime is 646655651. The reversal of 646655643 is 346556646.

It is not a de Polignac number, because 646655643 - 2⁹ = 646655131 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646655663) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 126858 + ... + 131856.

It is an arithmetic number, because the mean of its divisors is an integer number (48339500).

Almost surely, 2^646655643 is an apocalyptic number.

646655643 is a deficient number, since it is larger than the sum of its proper divisors (320134357).

646655643 is a wasteful number, since it uses less digits than its factorization.

646655643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6608 (or 6599 counting only the distinct ones).

The product of its digits is 1555200, while the sum is 45.

The square root of 646655643 is about 25429.4247477209. The cubic root of 646655643 is about 864.7509024677.

The spelling of 646655643 in words is "six hundred forty-six million, six hundred fifty-five thousand, six hundred forty-three".