721872 has 50 divisors (see below), whose sum is σ = 2093058. Its totient is φ = 240192.

The previous prime is 721859. The next prime is 721883. The reversal of 721872 is 278127.

It can be written as a sum of positive squares in only one way, i.e., 467856 + 254016 = 684^2 + 504^2 .

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an alternating number because its digits alternate between odd and even.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721872.

It is an unprimeable number.

721872 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 1018 + ... + 1574.

2⁷²¹⁸⁷² is an apocalyptic number.

721872 is a gapful number since it is divisible by the number (72) 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 721872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1046529).

721872 is an abundant number, since it is smaller than the sum of its proper divisors (1371186).

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

721872 is a wasteful number, since it uses less digits than its factorization.

721872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577 (or 562 counting only the distinct ones).

The product of its digits is 1568, while the sum is 27.

The square root of 721872 is about 849.6305079268. The cubic root of 721872 is about 89.7057053898.

Adding to 721872 its reverse (278127), we get a palindrome (999999).

The spelling of 721872 in words is "seven hundred twenty-one thousand, eight hundred seventy-two".