721331424 has 72 divisors (see below), whose sum is σ = 2237776632. Its totient is φ = 218584320.

The previous prime is 721331423. The next prime is 721331449. The reversal of 721331424 is 424133127.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721331423) 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, 110679 + ... + 117014.

It is an arithmetic number, because the mean of its divisors is an integer number (31080231).

Almost surely, 2^721331424 is an apocalyptic number.

It is an amenable number.

721331424 is an abundant number, since it is smaller than the sum of its proper divisors (1516445208).

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

721331424 is a wasteful number, since it uses less digits than its factorization.

721331424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227720 (or 227709 counting only the distinct ones).

The product of its digits is 4032, while the sum is 27.

The square root of 721331424 is about 26857.6138925259. The cubic root of 721331424 is about 896.8330766970.

The spelling of 721331424 in words is "seven hundred twenty-one million, three hundred thirty-one thousand, four hundred twenty-four".