724128781 has 2 divisors, whose sum is σ = 724128782. Its totient is φ = 724128780.

The previous prime is 724128767. The next prime is 724128809. The reversal of 724128781 is 187821427.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 427083556 + 297045225 = 20666^2 + 17235^2 .

It is a cyclic number.

It is not a de Polignac number, because 724128781 - 2⁵ = 724128749 is a prime.

It is a super-2 number, since 2×724128781² = 1048724982945091922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (724128761) 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, 362064390 + 362064391.

It is an arithmetic number, because the mean of its divisors is an integer number (362064391).

Almost surely, 2^724128781 is an apocalyptic number.

It is an amenable number.

724128781 is a deficient number, since it is larger than the sum of its proper divisors (1).

724128781 is an equidigital number, since it uses as much as digits as its factorization.

724128781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 50176, while the sum is 40.

The square root of 724128781 is about 26909.6410418274. The cubic root of 724128781 is about 897.9909014906.

The spelling of 724128781 in words is "seven hundred twenty-four million, one hundred twenty-eight thousand, seven hundred eighty-one".