721691473 has 2 divisors, whose sum is σ = 721691474. Its totient is φ = 721691472.

The previous prime is 721691461. The next prime is 721691491. The reversal of 721691473 is 374196127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 512252689 + 209438784 = 22633^2 + 14472^2 .

It is a cyclic number.

It is not a de Polignac number, because 721691473 - 2⁵ = 721691441 is a prime.

It is not a weakly prime, because it can be changed into another prime (721691423) 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, 360845736 + 360845737.

It is an arithmetic number, because the mean of its divisors is an integer number (360845737).

Almost surely, 2^721691473 is an apocalyptic number.

It is an amenable number.

721691473 is a deficient number, since it is larger than the sum of its proper divisors (1).

721691473 is an equidigital number, since it uses as much as digits as its factorization.

721691473 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 63504, while the sum is 40.

The square root of 721691473 is about 26864.3159786360. The cubic root of 721691473 is about 896.9822684699.

It can be divided in two parts, 7216 and 91473, that added together give a palindrome (98689).

The spelling of 721691473 in words is "seven hundred twenty-one million, six hundred ninety-one thousand, four hundred seventy-three".