721539139 has 2 divisors, whose sum is σ = 721539140. Its totient is φ = 721539138.

The previous prime is 721539113. The next prime is 721539173. The reversal of 721539139 is 931935127.

It is a weak prime.

It is an emirp because it is prime and its reverse (931935127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721539139 - 2⁵ = 721539107 is a prime.

It is a super-2 number, since 2×721539139² = 1041237458217722642, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (721539179) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360769569 + 360769570.

It is an arithmetic number, because the mean of its divisors is an integer number (360769570).

Almost surely, 2^721539139 is an apocalyptic number.

721539139 is a deficient number, since it is larger than the sum of its proper divisors (1).

721539139 is an equidigital number, since it uses as much as digits as its factorization.

721539139 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51030, while the sum is 40.

The square root of 721539139 is about 26861.4805809360. The cubic root of 721539139 is about 896.9191526200.

The spelling of 721539139 in words is "seven hundred twenty-one million, five hundred thirty-nine thousand, one hundred thirty-nine".