645699 has 16 divisors (see below), whose sum is σ = 912384. Its totient is φ = 405600.

The previous prime is 645691. The next prime is 645703. The reversal of 645699 is 996546.

645699 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 645699 - 2³ = 645691 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 645699.

It is not an unprimeable number, because it can be changed into a prime (645691) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4864 + ... + 4994.

It is an arithmetic number, because the mean of its divisors is an integer number (57024).

2⁶⁴⁵⁶⁹⁹ is an apocalyptic number.

645699 is a deficient number, since it is larger than the sum of its proper divisors (266685).

645699 is a wasteful number, since it uses less digits than its factorization.

645699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218.

The product of its digits is 58320, while the sum is 39.

The square root of 645699 is about 803.5539807630. The cubic root of 645699 is about 86.4324263147.

It can be divided in two parts, 6456 and 99, that added together give a triangular number (6555 = T₁₁₄).

The spelling of 645699 in words is "six hundred forty-five thousand, six hundred ninety-nine".