20057721 has 4 divisors (see below), whose sum is σ = 26743632. Its totient is φ = 13371812.

The previous prime is 20057717. The next prime is 20057729. The reversal of 20057721 is 12775002.

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 20057721 - 2² = 20057717 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 20057691 and 20057700.

It is not an unprimeable number, because it can be changed into a prime (20057729) 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, 3342951 + ... + 3342956.

It is an arithmetic number, because the mean of its divisors is an integer number (6685908).

Almost surely, 2^20057721 is an apocalyptic number.

It is an amenable number.

20057721 is a deficient number, since it is larger than the sum of its proper divisors (6685911).

20057721 is an equidigital number, since it uses as much as digits as its factorization.

20057721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6685910.

The product of its (nonzero) digits is 980, while the sum is 24.

The square root of 20057721 is about 4478.5847094813. The cubic root of 20057721 is about 271.7026423474.

The spelling of 20057721 in words is "twenty million, fifty-seven thousand, seven hundred twenty-one".