221441621 has 2 divisors, whose sum is σ = 221441622. Its totient is φ = 221441620.

The previous prime is 221441567. The next prime is 221441629. The reversal of 221441621 is 126144122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138886225 + 82555396 = 11785^2 + 9086^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221441621 is a prime.

It is a super-2 number, since 2×221441621² = 98072783022215282, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221441629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110720810 + 110720811.

It is an arithmetic number, because the mean of its divisors is an integer number (110720811).

Almost surely, 2^221441621 is an apocalyptic number.

It is an amenable number.

221441621 is a deficient number, since it is larger than the sum of its proper divisors (1).

221441621 is an equidigital number, since it uses as much as digits as its factorization.

221441621 is an evil number, because the sum of its binary digits is even.

The product of its digits is 768, while the sum is 23.

The square root of 221441621 is about 14880.9146560284. The cubic root of 221441621 is about 604.9968089443.

Adding to 221441621 its reverse (126144122), we get a palindrome (347585743).

The spelling of 221441621 in words is "two hundred twenty-one million, four hundred forty-one thousand, six hundred twenty-one".