27664721 has 4 divisors (see below), whose sum is σ = 31616832. Its totient is φ = 23712612.

The previous prime is 27664697. The next prime is 27664727. The reversal of 27664721 is 12746672.

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 27664721 - 2¹⁸ = 27402577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27664727) 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, 1976045 + ... + 1976058.

It is an arithmetic number, because the mean of its divisors is an integer number (7904208).

Almost surely, 2^27664721 is an apocalyptic number.

It is an amenable number.

27664721 is a deficient number, since it is larger than the sum of its proper divisors (3952111).

27664721 is an equidigital number, since it uses as much as digits as its factorization.

27664721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3952110.

The product of its digits is 28224, while the sum is 35.

The square root of 27664721 is about 5259.7263236788. The cubic root of 27664721 is about 302.4419978495.

The spelling of 27664721 in words is "twenty-seven million, six hundred sixty-four thousand, seven hundred twenty-one".