721403720 has 16 divisors (see below), whose sum is σ = 1623158460. Its totient is φ = 288561472.

The previous prime is 721403719. The next prime is 721403729. The reversal of 721403720 is 27304127.

It can be written as a sum of positive squares in 2 ways, for example, as 692005636 + 29398084 = 26306^2 + 5422^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 721403720.

It is not an unprimeable number, because it can be changed into a prime (721403729) 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, 9017507 + ... + 9017586.

Almost surely, 2^721403720 is an apocalyptic number.

It is an amenable number.

721403720 is an abundant number, since it is smaller than the sum of its proper divisors (901754740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721403720 is a wasteful number, since it uses less digits than its factorization.

721403720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18035104 (or 18035100 counting only the distinct ones).

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 721403720 is about 26858.9597713687. The cubic root of 721403720 is about 896.8630376257.

Adding to 721403720 its reverse (27304127), we get a palindrome (748707847).

The spelling of 721403720 in words is "seven hundred twenty-one million, four hundred three thousand, seven hundred twenty".