20427721 has 4 divisors (see below), whose sum is σ = 20482000. Its totient is φ = 20373444.

The previous prime is 20427707. The next prime is 20427763. The reversal of 20427721 is 12772402.

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 a cyclic number.

It is not a de Polignac number, because 20427721 - 2⁵ = 20427689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20427821) 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, 26571 + ... + 27328.

It is an arithmetic number, because the mean of its divisors is an integer number (5120500).

Almost surely, 2^20427721 is an apocalyptic number.

It is an amenable number.

20427721 is a deficient number, since it is larger than the sum of its proper divisors (54279).

20427721 is an equidigital number, since it uses as much as digits as its factorization.

20427721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54278.

The product of its (nonzero) digits is 1568, while the sum is 25.

The square root of 20427721 is about 4519.7036407269. The cubic root of 20427721 is about 273.3631514499.

The spelling of 20427721 in words is "twenty million, four hundred twenty-seven thousand, seven hundred twenty-one".