646990 has 32 divisors (see below), whose sum is σ = 1270080. Its totient is φ = 236544.

The previous prime is 646981. The next prime is 646991. The reversal of 646990 is 99646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646991) by changing a digit.

646990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6622 + ... + 6718.

It is an arithmetic number, because the mean of its divisors is an integer number (39690).

2⁶⁴⁶⁹⁹⁰ is an apocalyptic number.

646990 is a deficient number, since it is larger than the sum of its proper divisors (623090).

646990 is a wasteful number, since it uses less digits than its factorization.

646990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 646990 is about 804.3568859654. The cubic root of 646990 is about 86.4899918255.

The spelling of 646990 in words is "six hundred forty-six thousand, nine hundred ninety".