721340831 has 2 divisors, whose sum is σ = 721340832. Its totient is φ = 721340830.

The previous prime is 721340797. The next prime is 721340849. The reversal of 721340831 is 138043127.

It is a strong prime.

It is an emirp because it is prime and its reverse (138043127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721340831 - 2¹⁴ = 721324447 is a prime.

It is a super-2 number, since 2×721340831² = 1040665188935541122, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 721340794 and 721340803.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721340861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360670415 + 360670416.

It is an arithmetic number, because the mean of its divisors is an integer number (360670416).

Almost surely, 2^721340831 is an apocalyptic number.

721340831 is a deficient number, since it is larger than the sum of its proper divisors (1).

721340831 is an equidigital number, since it uses as much as digits as its factorization.

721340831 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 721340831 is about 26857.7890192026. The cubic root of 721340831 is about 896.8369752619.

Adding to 721340831 its reverse (138043127), we get a palindrome (859383958).

The spelling of 721340831 in words is "seven hundred twenty-one million, three hundred forty thousand, eight hundred thirty-one".