252221621 has 2 divisors, whose sum is σ = 252221622. Its totient is φ = 252221620.

The previous prime is 252221609. The next prime is 252221623. The reversal of 252221621 is 126122252.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 199092100 + 53129521 = 14110^2 + 7289^2 .

It is a cyclic number.

It is not a de Polignac number, because 252221621 - 2²⁶ = 185112757 is a prime.

It is a Sophie Germain prime.

Together with 252221623, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (252221623) 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, 126110810 + 126110811.

It is an arithmetic number, because the mean of its divisors is an integer number (126110811).

Almost surely, 2^252221621 is an apocalyptic number.

It is an amenable number.

252221621 is a deficient number, since it is larger than the sum of its proper divisors (1).

252221621 is an equidigital number, since it uses as much as digits as its factorization.

252221621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 960, while the sum is 23.

The square root of 252221621 is about 15881.4867377082. The cubic root of 252221621 is about 631.8210692589.

Adding to 252221621 its reverse (126122252), we get a palindrome (378343873).

The spelling of 252221621 in words is "two hundred fifty-two million, two hundred twenty-one thousand, six hundred twenty-one".