721695520 has 288 divisors, whose sum is σ = 2187522288. Its totient is φ = 222953472.

The previous prime is 721695517. The next prime is 721695521. The reversal of 721695520 is 25596127.

It can be written as a sum of positive squares in 8 ways, for example, as 182898576 + 538796944 = 13524^2 + 23212^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 721695520.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721695521) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 7440112 + ... + 7440208.

Almost surely, 2^721695520 is an apocalyptic number.

721695520 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 721695520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1093761144).

721695520 is an abundant number, since it is smaller than the sum of its proper divisors (1465826768).

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

721695520 is a wasteful number, since it uses less digits than its factorization.

721695520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212 (or 197 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 37.

The square root of 721695520 is about 26864.3913014980. The cubic root of 721695520 is about 896.9839451238.

The spelling of 721695520 in words is "seven hundred twenty-one million, six hundred ninety-five thousand, five hundred twenty".