721724640 has 576 divisors, whose sum is σ = 2975035392. Its totient is φ = 143769600.

The previous prime is 721724629. The next prime is 721724657. The reversal of 721724640 is 46427127.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 17603020 + ... + 17603060.

It is an arithmetic number, because the mean of its divisors is an integer number (5164992).

Almost surely, 2^721724640 is an apocalyptic number.

721724640 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721724640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1487517696).

721724640 is an abundant number, since it is smaller than the sum of its proper divisors (2253310752).

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

721724640 is a wasteful number, since it uses less digits than its factorization.

721724640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 102 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 33.

The square root of 721724640 is about 26864.9332774157. The cubic root of 721724640 is about 896.9960092240.

The spelling of 721724640 in words is "seven hundred twenty-one million, seven hundred twenty-four thousand, six hundred forty".