2638821 has 4 divisors (see below), whose sum is σ = 3518432. Its totient is φ = 1759212.

The previous prime is 2638793. The next prime is 2638841. The reversal of 2638821 is 1288362.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 2638821 - 2⁷ = 2638693 is a prime.

It is a D-number.

It is a Duffinian number.

2638821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2638841) 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, 439801 + ... + 439806.

It is an arithmetic number, because the mean of its divisors is an integer number (879608).

2^2638821 is an apocalyptic number.

It is an amenable number.

2638821 is a deficient number, since it is larger than the sum of its proper divisors (879611).

2638821 is an equidigital number, since it uses as much as digits as its factorization.

2638821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 879610.

The product of its digits is 4608, while the sum is 30.

The square root of 2638821 is about 1624.4448282413. Note that the first 3 decimals coincide. The cubic root of 2638821 is about 138.1878873221.

The spelling of 2638821 in words is "two million, six hundred thirty-eight thousand, eight hundred twenty-one".