721691449 has 2 divisors, whose sum is σ = 721691450. Its totient is φ = 721691448.

The previous prime is 721691441. The next prime is 721691461. The reversal of 721691449 is 944196127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 425679424 + 296012025 = 20632^2 + 17205^2 .

It is a cyclic number.

It is not a de Polignac number, because 721691449 - 2³ = 721691441 is a prime.

It is not a weakly prime, because it can be changed into another prime (721691441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360845724 + 360845725.

It is an arithmetic number, because the mean of its divisors is an integer number (360845725).

Almost surely, 2^721691449 is an apocalyptic number.

It is an amenable number.

721691449 is a deficient number, since it is larger than the sum of its proper divisors (1).

721691449 is an equidigital number, since it uses as much as digits as its factorization.

721691449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 43.

The square root of 721691449 is about 26864.3155319468. The cubic root of 721691449 is about 896.9822585268.

The spelling of 721691449 in words is "seven hundred twenty-one million, six hundred ninety-one thousand, four hundred forty-nine".