721715261 has 2 divisors, whose sum is σ = 721715262. Its totient is φ = 721715260.

The previous prime is 721715233. The next prime is 721715273. The reversal of 721715261 is 162517127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 709423225 + 12292036 = 26635^2 + 3506^2 .

It is a cyclic number.

It is not a de Polignac number, because 721715261 - 2¹⁴ = 721698877 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721715861) 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, 360857630 + 360857631.

It is an arithmetic number, because the mean of its divisors is an integer number (360857631).

Almost surely, 2^721715261 is an apocalyptic number.

It is an amenable number.

721715261 is a deficient number, since it is larger than the sum of its proper divisors (1).

721715261 is an equidigital number, since it uses as much as digits as its factorization.

721715261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5880, while the sum is 32.

The square root of 721715261 is about 26864.7587184400. The cubic root of 721715261 is about 896.9921236414.

The spelling of 721715261 in words is "seven hundred twenty-one million, seven hundred fifteen thousand, two hundred sixty-one".