721430389 has 2 divisors, whose sum is σ = 721430390. Its totient is φ = 721430388.

The previous prime is 721430387. The next prime is 721430417. The reversal of 721430389 is 983034127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 624250225 + 97180164 = 24985^2 + 9858^2 .

It is an emirp because it is prime and its reverse (983034127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721430389 - 2¹ = 721430387 is a prime.

Together with 721430387, it forms a pair of twin primes.

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721430387) 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, 360715194 + 360715195.

It is an arithmetic number, because the mean of its divisors is an integer number (360715195).

Almost surely, 2^721430389 is an apocalyptic number.

It is an amenable number.

721430389 is a deficient number, since it is larger than the sum of its proper divisors (1).

721430389 is an equidigital number, since it uses as much as digits as its factorization.

721430389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 721430389 is about 26859.4562305345. The cubic root of 721430389 is about 896.8740892948.

The spelling of 721430389 in words is "seven hundred twenty-one million, four hundred thirty thousand, three hundred eighty-nine".