646556 has 6 divisors (see below), whose sum is σ = 1131480. Its totient is φ = 323276.

The previous prime is 646549. The next prime is 646571. The reversal of 646556 is 655646.

It is a super-2 number, since 2×646556² = 836069322272, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80816 + ... + 80823.

It is an arithmetic number, because the mean of its divisors is an integer number (188580).

2⁶⁴⁶⁵⁵⁶ is an apocalyptic number.

It is an amenable number.

646556 is a deficient number, since it is larger than the sum of its proper divisors (484924).

646556 is a wasteful number, since it uses less digits than its factorization.

646556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161643 (or 161641 counting only the distinct ones).

The product of its digits is 21600, while the sum is 32.

The square root of 646556 is about 804.0870599630. The cubic root of 646556 is about 86.4706483772.

The spelling of 646556 in words is "six hundred forty-six thousand, five hundred fifty-six".