721650 has 48 divisors (see below), whose sum is σ = 1901664. Its totient is φ = 180480.

The previous prime is 721631. The next prime is 721661. The reversal of 721650 is 56127.

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

It is a congruent number.

It is an unprimeable number.

721650 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2409 + ... + 2691.

It is an arithmetic number, because the mean of its divisors is an integer number (39618).

2⁷²¹⁶⁵⁰ is an apocalyptic number.

It is a pronic number, being equal to 849×850.

It is a practical number, because each smaller number is the sum of distinct divisors of 721650, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (950832).

721650 is an abundant number, since it is smaller than the sum of its proper divisors (1180014).

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

721650 is a wasteful number, since it uses less digits than its factorization.

721650 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315 (or 310 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 721650 is about 849.4998528546. The cubic root of 721650 is about 89.6965086031.

Adding to 721650 its reverse (56127), we get a palindrome (777777).

The spelling of 721650 in words is "seven hundred twenty-one thousand, six hundred fifty".