721830 has 16 divisors (see below), whose sum is σ = 1732464. Its totient is φ = 192480.

The previous prime is 721793. The next prime is 721843. The reversal of 721830 is 38127.

721830 = T₃₉₆ + T₃₉₇ + ... + T₄₀₄.

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 = 721797 and 721806.

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 721830.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12001 + ... + 12060.

It is an arithmetic number, because the mean of its divisors is an integer number (108279).

2⁷²¹⁸³⁰ is an apocalyptic number.

721830 is an abundant number, since it is smaller than the sum of its proper divisors (1010634).

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

721830 is a wasteful number, since it uses less digits than its factorization.

721830 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24071.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 721830 is about 849.6057909407. The cubic root of 721830 is about 89.7039656018.

Adding to 721830 its reverse (38127), we get a palindrome (759957).

It can be divided in two parts, 721 and 830, that added together give a palindrome (1551).

The spelling of 721830 in words is "seven hundred twenty-one thousand, eight hundred thirty".