721517328 has 160 divisors (see below), whose sum is σ = 2376792320. Its totient is φ = 205286400.

The previous prime is 721517323. The next prime is 721517341. The reversal of 721517328 is 823715127.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 721517292 and 721517301.

It is not an unprimeable number, because it can be changed into a prime (721517323) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1200228 + ... + 1200828.

It is an arithmetic number, because the mean of its divisors is an integer number (14854952).

Almost surely, 2^721517328 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721517328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1188396160).

721517328 is an abundant number, since it is smaller than the sum of its proper divisors (1655274992).

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

721517328 is a wasteful number, since it uses less digits than its factorization.

721517328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1022 (or 1010 counting only the distinct ones).

The product of its digits is 23520, while the sum is 36.

The square root of 721517328 is about 26861.0745875886. The cubic root of 721517328 is about 896.9101150411.

The spelling of 721517328 in words is "seven hundred twenty-one million, five hundred seventeen thousand, three hundred twenty-eight".