22131721 has 2 divisors, whose sum is σ = 22131722. Its totient is φ = 22131720.

The previous prime is 22131709. The next prime is 22131731. The reversal of 22131721 is 12713122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19536400 + 2595321 = 4420^2 + 1611^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-22131721 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (22131731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11065860 + 11065861.

It is an arithmetic number, because the mean of its divisors is an integer number (11065861).

Almost surely, 2^22131721 is an apocalyptic number.

It is an amenable number.

22131721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22131721 is an equidigital number, since it uses as much as digits as its factorization.

22131721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168, while the sum is 19.

The square root of 22131721 is about 4704.4363105477. The cubic root of 22131721 is about 280.7620440481.

Adding to 22131721 its reverse (12713122), we get a palindrome (34844843).

The spelling of 22131721 in words is "twenty-two million, one hundred thirty-one thousand, seven hundred twenty-one".