721340 has 12 divisors (see below), whose sum is σ = 1514856. Its totient is φ = 288528.

The previous prime is 721337. The next prime is 721351. The reversal of 721340 is 43127.

It is a happy number.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18014 + ... + 18053.

It is an arithmetic number, because the mean of its divisors is an integer number (126238).

2⁷²¹³⁴⁰ is an apocalyptic number.

It is an amenable number.

721340 is an abundant number, since it is smaller than the sum of its proper divisors (793516).

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

721340 is a wasteful number, since it uses less digits than its factorization.

721340 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36076 (or 36074 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 721340 is about 849.3173729531. The cubic root of 721340 is about 89.6836630870.

Adding to 721340 its reverse (43127), we get a palindrome (764467).

The spelling of 721340 in words is "seven hundred twenty-one thousand, three hundred forty", and thus it is an iban number.