721336 has 32 divisors (see below), whose sum is σ = 1687680. Its totient is φ = 280800.

The previous prime is 721333. The next prime is 721337. The reversal of 721336 is 633127.

721336 = T₂₄₅ + T₂₄₆ + ... + T₂₆₆.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721333) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31 + ... + 1201.

It is an arithmetic number, because the mean of its divisors is an integer number (52740).

2⁷²¹³³⁶ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (843840).

721336 is an abundant number, since it is smaller than the sum of its proper divisors (966344).

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

721336 is a wasteful number, since it uses less digits than its factorization.

721336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1195 (or 1191 counting only the distinct ones).

The product of its digits is 756, while the sum is 22.

The square root of 721336 is about 849.3150181175. The cubic root of 721336 is about 89.6834973144.

Subtracting from 721336 its reverse (633127), we obtain a square (88209 = 297²).

The spelling of 721336 in words is "seven hundred twenty-one thousand, three hundred thirty-six".