721330421 has 12 divisors (see below), whose sum is σ = 883262880. Its totient is φ = 585741240.

The previous prime is 721330403. The next prime is 721330453. The reversal of 721330421 is 124033127.

It is a de Polignac number, because none of the positive numbers 2^k-721330421 is a prime.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721330721) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 386465 + ... + 388326.

It is an arithmetic number, because the mean of its divisors is an integer number (73605240).

Almost surely, 2^721330421 is an apocalyptic number.

It is an amenable number.

721330421 is a deficient number, since it is larger than the sum of its proper divisors (161932459).

721330421 is a wasteful number, since it uses less digits than its factorization.

721330421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 774824 (or 774817 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 721330421 is about 26857.5952199746. The cubic root of 721330421 is about 896.8326610194.

Adding to 721330421 its reverse (124033127), we get a palindrome (845363548).

The spelling of 721330421 in words is "seven hundred twenty-one million, three hundred thirty thousand, four hundred twenty-one".