221794810379521 has 2 divisors, whose sum is σ = 221794810379522. Its totient is φ = 221794810379520.

The previous prime is 221794810379507. The next prime is 221794810379567. The reversal of 221794810379521 is 125973018497122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 167459645984400 + 54335164395121 = 12940620^2 + 7371239^2 .

It is a cyclic number.

It is not a de Polignac number, because 221794810379521 - 2¹⁷ = 221794810248449 is a prime.

It is a super-2 number, since 2×221794810379521² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221794810379521.

It is not a weakly prime, because it can be changed into another prime (221794810379921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110897405189760 + 110897405189761.

It is an arithmetic number, because the mean of its divisors is an integer number (110897405189761).

Almost surely, 2^{221794810379521} is an apocalyptic number.

It is an amenable number.

221794810379521 is a deficient number, since it is larger than the sum of its proper divisors (1).

221794810379521 is an equidigital number, since it uses as much as digits as its factorization.

221794810379521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15240960, while the sum is 61.

The spelling of 221794810379521 in words is "two hundred twenty-one trillion, seven hundred ninety-four billion, eight hundred ten million, three hundred seventy-nine thousand, five hundred twenty-one".