721230421 has 4 divisors (see below), whose sum is σ = 730360000. Its totient is φ = 712100844.

The previous prime is 721230403. The next prime is 721230439. The reversal of 721230421 is 124032127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (721230403) and next prime (721230439).

It is a cyclic number.

It is not a de Polignac number, because 721230421 - 2¹¹ = 721228373 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721230392 and 721230401.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721230401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4564671 + ... + 4564828.

It is an arithmetic number, because the mean of its divisors is an integer number (182590000).

Almost surely, 2^721230421 is an apocalyptic number.

It is an amenable number.

721230421 is a deficient number, since it is larger than the sum of its proper divisors (9129579).

721230421 is an equidigital number, since it uses as much as digits as its factorization.

721230421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9129578.

The product of its (nonzero) digits is 672, while the sum is 22.

The square root of 721230421 is about 26855.7334846770. The cubic root of 721230421 is about 896.7912156530.

Adding to 721230421 its reverse (124032127), we get a palindrome (845262548).

The spelling of 721230421 in words is "seven hundred twenty-one million, two hundred thirty thousand, four hundred twenty-one".