721616503 has 4 divisors (see below), whose sum is σ = 722593720. Its totient is φ = 720639288.

The previous prime is 721616501. The next prime is 721616537. The reversal of 721616503 is 305616127.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 721616503 - 2¹ = 721616501 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721616501) 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, 487500 + ... + 488977.

It is an arithmetic number, because the mean of its divisors is an integer number (180648430).

Almost surely, 2^721616503 is an apocalyptic number.

721616503 is a deficient number, since it is larger than the sum of its proper divisors (977217).

721616503 is an equidigital number, since it uses as much as digits as its factorization.

721616503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 977216.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 721616503 is about 26862.9205969865. The cubic root of 721616503 is about 896.9512076026.

The spelling of 721616503 in words is "seven hundred twenty-one million, six hundred sixteen thousand, five hundred three".