721691461 has 2 divisors, whose sum is σ = 721691462. Its totient is φ = 721691460.

The previous prime is 721691449. The next prime is 721691473. The reversal of 721691461 is 164196127.

It is a balanced prime because it is at equal distance from previous prime (721691449) and next prime (721691473).

It can be written as a sum of positive squares in only one way, i.e., 572118561 + 149572900 = 23919^2 + 12230^2 .

It is an emirp because it is prime and its reverse (164196127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721691461 - 2¹¹ = 721689413 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 721691461.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721691441) 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, 360845730 + 360845731.

It is an arithmetic number, because the mean of its divisors is an integer number (360845731).

Almost surely, 2^721691461 is an apocalyptic number.

It is an amenable number.

721691461 is a deficient number, since it is larger than the sum of its proper divisors (1).

721691461 is an equidigital number, since it uses as much as digits as its factorization.

721691461 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 721691461 is about 26864.3157552914. The cubic root of 721691461 is about 896.9822634984.

The spelling of 721691461 in words is "seven hundred twenty-one million, six hundred ninety-one thousand, four hundred sixty-one".