721216 has 28 divisors (see below), whose sum is σ = 1463040. Its totient is φ = 352640.

The previous prime is 721213. The next prime is 721219. The reversal of 721216 is 612127.

It is an interprime number because it is at equal distance from previous prime (721213) and next prime (721219).

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

It is a junction number, because it is equal to n+sod(n) for n = 721193 and 721202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3681 + ... + 3871.

2⁷²¹²¹⁶ 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 721216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (731520).

721216 is an abundant number, since it is smaller than the sum of its proper divisors (741824).

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

721216 is a wasteful number, since it uses less digits than its factorization.

721216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 262 (or 252 counting only the distinct ones).

The product of its digits is 168, while the sum is 19.

The square root of 721216 is about 849.2443700137. The cubic root of 721216 is about 89.6785238501.

It can be divided in two parts, 72121 and 6, that added together give a palindrome (72127).

The spelling of 721216 in words is "seven hundred twenty-one thousand, two hundred sixteen".