721630 has 48 divisors (see below), whose sum is σ = 1633824. Its totient is φ = 224640.

The previous prime is 721621. The next prime is 721631. The reversal of 721630 is 36127.

721630 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 = 721598 and 721607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721631) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11800 + ... + 11860.

It is an arithmetic number, because the mean of its divisors is an integer number (34038).

2⁷²¹⁶³⁰ is an apocalyptic number.

721630 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

721630 is an abundant number, since it is smaller than the sum of its proper divisors (912194).

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

721630 is a wasteful number, since it uses less digits than its factorization.

721630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101 (or 88 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 19.

The square root of 721630 is about 849.4880811406. The cubic root of 721630 is about 89.6956799712.

Adding to 721630 its reverse (36127), we get a palindrome (757757).

The spelling of 721630 in words is "seven hundred twenty-one thousand, six hundred thirty".