27920721 has 4 divisors (see below), whose sum is σ = 37227632. Its totient is φ = 18613812.

The previous prime is 27920719. The next prime is 27920779. The reversal of 27920721 is 12702972.

It is a happy number.

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 27920721 - 2¹ = 27920719 is a prime.

It is a super-2 number, since 2×27920721² = 1559133322319682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (27925721) 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, 4653451 + ... + 4653456.

It is an arithmetic number, because the mean of its divisors is an integer number (9306908).

Almost surely, 2^27920721 is an apocalyptic number.

It is an amenable number.

27920721 is a deficient number, since it is larger than the sum of its proper divisors (9306911).

27920721 is an equidigital number, since it uses as much as digits as its factorization.

27920721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9306910.

The product of its (nonzero) digits is 3528, while the sum is 30.

The square root of 27920721 is about 5284.0061506399. The cubic root of 27920721 is about 303.3720337318.

The spelling of 27920721 in words is "twenty-seven million, nine hundred twenty thousand, seven hundred twenty-one".