402639 has 4 divisors (see below), whose sum is σ = 536856. Its totient is φ = 268424.

The previous prime is 402631. The next prime is 402691. The reversal of 402639 is 936204.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 402639 - 2³ = 402631 is a prime.

It is a D-number.

It is a plaindrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (402631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67104 + ... + 67109.

It is an arithmetic number, because the mean of its divisors is an integer number (134214).

2⁴⁰²⁶³⁹ is an apocalyptic number.

402639 is a deficient number, since it is larger than the sum of its proper divisors (134217).

402639 is a wasteful number, since it uses less digits than its factorization.

402639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134216.

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 402639 is about 634.5384149128. The cubic root of 402639 is about 73.8423109145.

The spelling of 402639 in words is "four hundred two thousand, six hundred thirty-nine".