13872821 has 4 divisors (see below), whose sum is σ = 13888332. Its totient is φ = 13857312.

The previous prime is 13872809. The next prime is 13872829. The reversal of 13872821 is 12827831.

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

It can be written as a sum of positive squares in 2 ways, for example, as 3880900 + 9991921 = 1970^2 + 3161^2 .

It is a cyclic number.

It is not a de Polignac number, because 13872821 - 2²² = 9678517 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13872829) 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, 6326 + ... + 8231.

It is an arithmetic number, because the mean of its divisors is an integer number (3472083).

Almost surely, 2^13872821 is an apocalyptic number.

It is an amenable number.

13872821 is a deficient number, since it is larger than the sum of its proper divisors (15511).

13872821 is an equidigital number, since it uses as much as digits as its factorization.

13872821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15510.

The product of its digits is 5376, while the sum is 32.

The square root of 13872821 is about 3724.6236051446. The cubic root of 13872821 is about 240.2821969920.

The spelling of 13872821 in words is "thirteen million, eight hundred seventy-two thousand, eight hundred twenty-one".