22051721 has 2 divisors, whose sum is σ = 22051722. Its totient is φ = 22051720.

The previous prime is 22051717. The next prime is 22051739. The reversal of 22051721 is 12715022.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13957696 + 8094025 = 3736^2 + 2845^2 .

It is a cyclic number.

It is not a de Polignac number, because 22051721 - 2² = 22051717 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 22051693 and 22051702.

It is not a weakly prime, because it can be changed into another prime (22051751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11025860 + 11025861.

It is an arithmetic number, because the mean of its divisors is an integer number (11025861).

Almost surely, 2^22051721 is an apocalyptic number.

It is an amenable number.

22051721 is a deficient number, since it is larger than the sum of its proper divisors (1).

22051721 is an equidigital number, since it uses as much as digits as its factorization.

22051721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 280, while the sum is 20.

The square root of 22051721 is about 4695.9260002687. The cubic root of 22051721 is about 280.4233434507.

Adding to 22051721 its reverse (12715022), we get a palindrome (34766743).

The spelling of 22051721 in words is "twenty-two million, fifty-one thousand, seven hundred twenty-one".