721312 has 12 divisors (see below), whose sum is σ = 1420146. Its totient is φ = 360640.

The previous prime is 721307. The next prime is 721319. The reversal of 721312 is 213127.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 524176 + 197136 = 724^2 + 444^2 .

It is a hoax number, since the sum of its digits (16) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is not an unprimeable number, because it can be changed into a prime (721319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11239 + ... + 11302.

2⁷²¹³¹² is an apocalyptic number.

It is an amenable number.

721312 is a deficient number, since it is larger than the sum of its proper divisors (698834).

721312 is a wasteful number, since it uses less digits than its factorization.

721312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22551 (or 22543 counting only the distinct ones).

The product of its digits is 84, while the sum is 16.

The square root of 721312 is about 849.3008889669. The cubic root of 721312 is about 89.6825026656.

Adding to 721312 its reverse (213127), we get a palindrome (934439).

It can be divided in two parts, 7213 and 12, that added together give a square (7225 = 85²).

The spelling of 721312 in words is "seven hundred twenty-one thousand, three hundred twelve", and thus it is an iban number.