721439 has 2 divisors, whose sum is σ = 721440. Its totient is φ = 721438.

The previous prime is 721397. The next prime is 721451. The reversal of 721439 is 934127.

It is a strong prime.

It is an emirp because it is prime and its reverse (934127) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721439 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360719 + 360720.

It is an arithmetic number, because the mean of its divisors is an integer number (360720).

2⁷²¹⁴³⁹ is an apocalyptic number.

721439 is a deficient number, since it is larger than the sum of its proper divisors (1).

721439 is an equidigital number, since it uses as much as digits as its factorization.

721439 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1512, while the sum is 26.

The square root of 721439 is about 849.3756530535. The cubic root of 721439 is about 89.6877657647.

The spelling of 721439 in words is "seven hundred twenty-one thousand, four hundred thirty-nine".