721932221 has 2 divisors, whose sum is σ = 721932222. Its totient is φ = 721932220.

The previous prime is 721932199. The next prime is 721932269. The reversal of 721932221 is 122239127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 483384196 + 238548025 = 21986^2 + 15445^2 .

It is a cyclic number.

It is not a de Polignac number, because 721932221 - 2⁶ = 721932157 is a prime.

It is a super-2 number, since 2×721932221² = 1042372263435985682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721934221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360966110 + 360966111.

It is an arithmetic number, because the mean of its divisors is an integer number (360966111).

Almost surely, 2^721932221 is an apocalyptic number.

It is an amenable number.

721932221 is a deficient number, since it is larger than the sum of its proper divisors (1).

721932221 is an equidigital number, since it uses as much as digits as its factorization.

721932221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 29.

The square root of 721932221 is about 26868.7964188945. The cubic root of 721932221 is about 897.0819983809.

The spelling of 721932221 in words is "seven hundred twenty-one million, nine hundred thirty-two thousand, two hundred twenty-one".