645916 has 12 divisors (see below), whose sum is σ = 1167040. Its totient is φ = 312480.

The previous prime is 645907. The next prime is 645937. The reversal of 645916 is 619546.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2481 + ... + 2728.

2⁶⁴⁵⁹¹⁶ is an apocalyptic number.

It is an amenable number.

645916 is a deficient number, since it is larger than the sum of its proper divisors (521124).

645916 is a wasteful number, since it uses less digits than its factorization.

645916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5244 (or 5242 counting only the distinct ones).

The product of its digits is 6480, while the sum is 31.

The square root of 645916 is about 803.6889945744. The cubic root of 645916 is about 86.4421076759.

The spelling of 645916 in words is "six hundred forty-five thousand, nine hundred sixteen".