2521639 has 4 divisors (see below), whose sum is σ = 2556256. Its totient is φ = 2487024.

The previous prime is 2521621. The next prime is 2521643. The reversal of 2521639 is 9361252.

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 2521639 - 2¹¹ = 2519591 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2521609) 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, 17199 + ... + 17344.

It is an arithmetic number, because the mean of its divisors is an integer number (639064).

2^2521639 is an apocalyptic number.

2521639 is a deficient number, since it is larger than the sum of its proper divisors (34617).

2521639 is an equidigital number, since it uses as much as digits as its factorization.

2521639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34616.

The product of its digits is 3240, while the sum is 28.

The square root of 2521639 is about 1587.9669392025. The cubic root of 2521639 is about 136.1113383247. Note that the first 3 decimals are identical.

It can be divided in two parts, 2521 and 639, that added together give a triangular number (3160 = T₇₉).

The spelling of 2521639 in words is "two million, five hundred twenty-one thousand, six hundred thirty-nine".