978639 has 16 divisors (see below), whose sum is σ = 1428480. Its totient is φ = 593280.

The previous prime is 978619. The next prime is 978643. The reversal of 978639 is 936879.

It is a happy number.

It is not a de Polignac number, because 978639 - 2⁷ = 978511 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 978639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (978619) 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, 1272 + ... + 1890.

It is an arithmetic number, because the mean of its divisors is an integer number (89280).

2⁹⁷⁸⁶³⁹ is an apocalyptic number.

978639 is a deficient number, since it is larger than the sum of its proper divisors (449841).

978639 is a wasteful number, since it uses less digits than its factorization.

978639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 670.

The product of its digits is 81648, while the sum is 42.

The square root of 978639 is about 989.2618460246. The cubic root of 978639 is about 99.2828357157.

The spelling of 978639 in words is "nine hundred seventy-eight thousand, six hundred thirty-nine".