721436 has 24 divisors (see below), whose sum is σ = 1333584. Its totient is φ = 341120.

The previous prime is 721397. The next prime is 721439. The reversal of 721436 is 634127.

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

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 721436.

It is not an unprimeable number, because it can be changed into a prime (721439) by changing a digit.

721436 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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 7 ways as a sum of consecutive naturals, for example, 8651 + ... + 8733.

It is an arithmetic number, because the mean of its divisors is an integer number (55566).

2⁷²¹⁴³⁶ is an apocalyptic number.

It is an amenable number.

721436 is a deficient number, since it is larger than the sum of its proper divisors (612148).

721436 is a wasteful number, since it uses less digits than its factorization.

721436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181 (or 179 counting only the distinct ones).

The product of its digits is 1008, while the sum is 23.

The square root of 721436 is about 849.3738870486. The cubic root of 721436 is about 89.6876414466.

The spelling of 721436 in words is "seven hundred twenty-one thousand, four hundred thirty-six".