664687 has 2 divisors, whose sum is σ = 664688. Its totient is φ = 664686.

The previous prime is 664679. The next prime is 664691. The reversal of 664687 is 786466.

664687 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 664687 - 2³ = 664679 is a prime.

664687 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332343 + 332344.

It is an arithmetic number, because the mean of its divisors is an integer number (332344).

2⁶⁶⁴⁶⁸⁷ is an apocalyptic number.

664687 is a deficient number, since it is larger than the sum of its proper divisors (1).

664687 is an equidigital number, since it uses as much as digits as its factorization.

664687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 48384, while the sum is 37.

The square root of 664687 is about 815.2833863142. The cubic root of 664687 is about 87.2714908350.

It can be divided in two parts, 66 and 4687, that added together give a triangular number (4753 = T₉₇).

The spelling of 664687 in words is "six hundred sixty-four thousand, six hundred eighty-seven".