27639921 has 4 divisors (see below), whose sum is σ = 36853232. Its totient is φ = 18426612.

The previous prime is 27639883. The next prime is 27639923. The reversal of 27639921 is 12993672.

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 27639921 - 2⁷ = 27639793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 27639921.

It is not an unprimeable number, because it can be changed into a prime (27639923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4606651 + ... + 4606656.

It is an arithmetic number, because the mean of its divisors is an integer number (9213308).

Almost surely, 2^27639921 is an apocalyptic number.

It is an amenable number.

27639921 is a deficient number, since it is larger than the sum of its proper divisors (9213311).

27639921 is an equidigital number, since it uses as much as digits as its factorization.

27639921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9213310.

The product of its digits is 40824, while the sum is 39.

The square root of 27639921 is about 5257.3682579785. The cubic root of 27639921 is about 302.3515962636.

The spelling of 27639921 in words is "twenty-seven million, six hundred thirty-nine thousand, nine hundred twenty-one".