20331721 has 2 divisors, whose sum is σ = 20331722. Its totient is φ = 20331720.

The previous prime is 20331679. The next prime is 20331739. The reversal of 20331721 is 12713302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16088121 + 4243600 = 4011^2 + 2060^2 .

It is a cyclic number.

It is not a de Polignac number, because 20331721 - 2⁹ = 20331209 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20331761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10165860 + 10165861.

It is an arithmetic number, because the mean of its divisors is an integer number (10165861).

Almost surely, 2^20331721 is an apocalyptic number.

It is an amenable number.

20331721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20331721 is an equidigital number, since it uses as much as digits as its factorization.

20331721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 20331721 is about 4509.0709686143. The cubic root of 20331721 is about 272.9342558392.

The spelling of 20331721 in words is "twenty million, three hundred thirty-one thousand, seven hundred twenty-one".