20112721 has 2 divisors, whose sum is σ = 20112722. Its totient is φ = 20112720.

The previous prime is 20112661. The next prime is 20112727. The reversal of 20112721 is 12721102.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10471696 + 9641025 = 3236^2 + 3105^2 .

It is a cyclic number.

It is not a de Polignac number, because 20112721 - 2¹⁷ = 19981649 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20112695 and 20112704.

It is not a weakly prime, because it can be changed into another prime (20112727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10056360 + 10056361.

It is an arithmetic number, because the mean of its divisors is an integer number (10056361).

Almost surely, 2^20112721 is an apocalyptic number.

It is an amenable number.

20112721 is a deficient number, since it is larger than the sum of its proper divisors (1).

20112721 is an equidigital number, since it uses as much as digits as its factorization.

20112721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 20112721 is about 4484.7208385807. The cubic root of 20112721 is about 271.9507597212.

Adding to 20112721 its reverse (12721102), we get a palindrome (32833823).

The spelling of 20112721 in words is "twenty million, one hundred twelve thousand, seven hundred twenty-one".