721667513 has 4 divisors (see below), whose sum is σ = 824762880. Its totient is φ = 618572148.

The previous prime is 721667509. The next prime is 721667537. The reversal of 721667513 is 315766127.

721667513 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721667513 - 2² = 721667509 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721667503) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51547673 + ... + 51547686.

It is an arithmetic number, because the mean of its divisors is an integer number (206190720).

Almost surely, 2^721667513 is an apocalyptic number.

It is an amenable number.

721667513 is a deficient number, since it is larger than the sum of its proper divisors (103095367).

721667513 is a wasteful number, since it uses less digits than its factorization.

721667513 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103095366.

The product of its digits is 52920, while the sum is 38.

The square root of 721667513 is about 26863.8700302097. The cubic root of 721667513 is about 896.9723418213.

The spelling of 721667513 in words is "seven hundred twenty-one million, six hundred sixty-seven thousand, five hundred thirteen".