402644639 has 2 divisors, whose sum is σ = 402644640. Its totient is φ = 402644638.

The previous prime is 402644611. The next prime is 402644653. The reversal of 402644639 is 936446204.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 402644639 - 2⁸ = 402644383 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (402644659) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 201322319 + 201322320.

It is an arithmetic number, because the mean of its divisors is an integer number (201322320).

Almost surely, 2^402644639 is an apocalyptic number.

402644639 is a deficient number, since it is larger than the sum of its proper divisors (1).

402644639 is an equidigital number, since it uses as much as digits as its factorization.

402644639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 124416, while the sum is 38.

The square root of 402644639 is about 20066.0070517281. The cubic root of 402644639 is about 738.4265563587.

The spelling of 402644639 in words is "four hundred two million, six hundred forty-four thousand, six hundred thirty-nine".