721691459 has 4 divisors (see below), whose sum is σ = 759675240. Its totient is φ = 683707680.

The previous prime is 721691449. The next prime is 721691461. The reversal of 721691459 is 954196127.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 954196127 = 3323 ⋅287149.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721691459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721691449) 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 in 3 ways as a sum of consecutive naturals, for example, 18991862 + ... + 18991899.

It is an arithmetic number, because the mean of its divisors is an integer number (189918810).

Almost surely, 2^721691459 is an apocalyptic number.

721691459 is a deficient number, since it is larger than the sum of its proper divisors (37983781).

721691459 is a wasteful number, since it uses less digits than its factorization.

721691459 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37983780.

The product of its digits is 136080, while the sum is 44.

The square root of 721691459 is about 26864.3157180673. The cubic root of 721691459 is about 896.9822626698.

The spelling of 721691459 in words is "seven hundred twenty-one million, six hundred ninety-one thousand, four hundred fifty-nine".