2978639 has 4 divisors (see below), whose sum is σ = 2984256. Its totient is φ = 2973024.

The previous prime is 2978629. The next prime is 2978681. The reversal of 2978639 is 9368792.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2978639 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2978639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2978629) 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, 1919 + ... + 3104.

It is an arithmetic number, because the mean of its divisors is an integer number (746064).

2^2978639 is an apocalyptic number.

2978639 is a deficient number, since it is larger than the sum of its proper divisors (5617).

2978639 is an equidigital number, since it uses as much as digits as its factorization.

2978639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5616.

The product of its digits is 163296, while the sum is 44.

The square root of 2978639 is about 1725.8734020779. The cubic root of 2978639 is about 143.8818314249.

The spelling of 2978639 in words is "two million, nine hundred seventy-eight thousand, six hundred thirty-nine".