2721639 has 4 divisors (see below), whose sum is σ = 3628856. Its totient is φ = 1814424.

The previous prime is 2721619. The next prime is 2721671. The reversal of 2721639 is 9361272.

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

It is not a de Polignac number, because 2721639 - 2⁹ = 2721127 is a prime.

It is a D-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 (2721619) 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, 453604 + ... + 453609.

It is an arithmetic number, because the mean of its divisors is an integer number (907214).

2^2721639 is an apocalyptic number.

2721639 is a deficient number, since it is larger than the sum of its proper divisors (907217).

2721639 is an equidigital number, since it uses as much as digits as its factorization.

2721639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 907216.

The product of its digits is 4536, while the sum is 30.

The square root of 2721639 is about 1649.7390702775. The cubic root of 2721639 is about 139.6186731835.

The spelling of 2721639 in words is "two million, seven hundred twenty-one thousand, six hundred thirty-nine".