646690 has 16 divisors (see below), whose sum is σ = 1270080. Its totient is φ = 235120.

The previous prime is 646687. The next prime is 646721. The reversal of 646690 is 96646.

646690 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×646690² = 836415912200, which contains 22 as substring.

It is an Ulam number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2830 + ... + 3049.

It is an arithmetic number, because the mean of its divisors is an integer number (79380).

2⁶⁴⁶⁶⁹⁰ is an apocalyptic number.

646690 is a deficient number, since it is larger than the sum of its proper divisors (623390).

646690 is a wasteful number, since it uses less digits than its factorization.

646690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5897.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 646690 is about 804.1703799569. The cubic root of 646690 is about 86.4766217018.

It can be divided in two parts, 6466 and 90, that added together give a palindrome (6556).

The spelling of 646690 in words is "six hundred forty-six thousand, six hundred ninety".