721447381 has 2 divisors, whose sum is σ = 721447382. Its totient is φ = 721447380.

The previous prime is 721447373. The next prime is 721447403. The reversal of 721447381 is 183744127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 663062500 + 58384881 = 25750^2 + 7641^2 .

It is a cyclic number.

It is not a de Polignac number, because 721447381 - 2³ = 721447373 is a prime.

It is a super-2 number, since 2×721447381² = 1040972647103518322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721447381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721447351) 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, 360723690 + 360723691.

It is an arithmetic number, because the mean of its divisors is an integer number (360723691).

Almost surely, 2^721447381 is an apocalyptic number.

It is an amenable number.

721447381 is a deficient number, since it is larger than the sum of its proper divisors (1).

721447381 is an equidigital number, since it uses as much as digits as its factorization.

721447381 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37632, while the sum is 37.

The square root of 721447381 is about 26859.7725418515. The cubic root of 721447381 is about 896.8811306602.

The spelling of 721447381 in words is "seven hundred twenty-one million, four hundred forty-seven thousand, three hundred eighty-one".