721632 has 24 divisors (see below), whose sum is σ = 1894536. Its totient is φ = 240512.

The previous prime is 721631. The next prime is 721661. The reversal of 721632 is 236127.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (24).

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 = 721599 and 721608.

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 721632.

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

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3663 + ... + 3854.

It is an arithmetic number, because the mean of its divisors is an integer number (78939).

2⁷²¹⁶³² is an apocalyptic number.

It is an amenable number.

721632 is an abundant number, since it is smaller than the sum of its proper divisors (1172904).

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

721632 is a wasteful number, since it uses less digits than its factorization.

721632 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7530 (or 7522 counting only the distinct ones).

The product of its digits is 504, while the sum is 21.

The square root of 721632 is about 849.4892583194. The cubic root of 721632 is about 89.6957628351.

Adding to 721632 its reverse (236127), we get a palindrome (957759).

The spelling of 721632 in words is "seven hundred twenty-one thousand, six hundred thirty-two".