722640 has 40 divisors (see below), whose sum is σ = 2240928. Its totient is φ = 192640.

The previous prime is 722639. The next prime is 722663. The reversal of 722640 is 46227.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (21) coincides with the sum of the digits of its prime factors.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1266 + ... + 1745.

2⁷²²⁶⁴⁰ is an apocalyptic number.

It is an amenable number.

722640 is an abundant number, since it is smaller than the sum of its proper divisors (1518288).

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

722640 is a wasteful number, since it uses less digits than its factorization.

722640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3027 (or 3021 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 722640 is about 850.0823489521. The cubic root of 722640 is about 89.7375067637.

Adding to 722640 its reverse (46227), we get a palindrome (768867).

The spelling of 722640 in words is "seven hundred twenty-two thousand, six hundred forty".