721624649 has 2 divisors, whose sum is σ = 721624650. Its totient is φ = 721624648.

The previous prime is 721624643. The next prime is 721624669. The reversal of 721624649 is 946426127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 659719225 + 61905424 = 25685^2 + 7868^2 .

It is an emirp because it is prime and its reverse (946426127) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721624649 is a prime.

It is not a weakly prime, because it can be changed into another prime (721624643) 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, 360812324 + 360812325.

It is an arithmetic number, because the mean of its divisors is an integer number (360812325).

Almost surely, 2^721624649 is an apocalyptic number.

It is an amenable number.

721624649 is a deficient number, since it is larger than the sum of its proper divisors (1).

721624649 is an equidigital number, since it uses as much as digits as its factorization.

721624649 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 41.

The square root of 721624649 is about 26863.0722181957. The cubic root of 721624649 is about 896.9545826811.

The spelling of 721624649 in words is "seven hundred twenty-one million, six hundred twenty-four thousand, six hundred forty-nine".