721430 has 16 divisors (see below), whose sum is σ = 1367280. Its totient is φ = 273312.

The previous prime is 721397. The next prime is 721439. The reversal of 721430 is 34127.

It is a happy number.

It is a super-2 number, since 2×721430² = 1040922489800, which contains 22 as substring.

It is an Ulam number.

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 = 721399 and 721408.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721439) 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 7 ways as a sum of consecutive naturals, for example, 1709 + ... + 2088.

It is an arithmetic number, because the mean of its divisors is an integer number (85455).

2⁷²¹⁴³⁰ is an apocalyptic number.

721430 is a deficient number, since it is larger than the sum of its proper divisors (645850).

721430 is a wasteful number, since it uses less digits than its factorization.

721430 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3823.

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

The square root of 721430 is about 849.3703550278. The cubic root of 721430 is about 89.6873928095.

Adding to 721430 its reverse (34127), we get a palindrome (755557).

The spelling of 721430 in words is "seven hundred twenty-one thousand, four hundred thirty".