2556639 has 12 divisors (see below), whose sum is σ = 3745872. Its totient is φ = 1680000.

The previous prime is 2556607. The next prime is 2556641. The reversal of 2556639 is 9366552.

It is not a de Polignac number, because 2556639 - 2⁵ = 2556607 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2556689) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1362 + ... + 2639.

It is an arithmetic number, because the mean of its divisors is an integer number (312156).

2^2556639 is an apocalyptic number.

2556639 is a deficient number, since it is larger than the sum of its proper divisors (1189233).

2556639 is a wasteful number, since it uses less digits than its factorization.

2556639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4078 (or 4075 counting only the distinct ones).

The product of its digits is 48600, while the sum is 36.

The square root of 2556639 is about 1598.9493425372. The cubic root of 2556639 is about 136.7381825450.

It can be divided in two parts, 2556 and 639, that multiplied together give a square (1633284 = 1278²).

The spelling of 2556639 in words is "two million, five hundred fifty-six thousand, six hundred thirty-nine".