2081639 has 4 divisors (see below), whose sum is σ = 2379024. Its totient is φ = 1784256.

The previous prime is 2081627. The next prime is 2081647. The reversal of 2081639 is 9361802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9361802 = 2 ⋅4680901.

It is a cyclic number.

It is not a de Polignac number, because 2081639 - 2⁸ = 2081383 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 (2081609) 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, 148682 + ... + 148695.

It is an arithmetic number, because the mean of its divisors is an integer number (594756).

2^2081639 is an apocalyptic number.

2081639 is a deficient number, since it is larger than the sum of its proper divisors (297385).

2081639 is an equidigital number, since it uses as much as digits as its factorization.

2081639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297384.

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 2081639 is about 1442.7886193064. The cubic root of 2081639 is about 127.6836057787.

The spelling of 2081639 in words is "two million, eighty-one thousand, six hundred thirty-nine".