721402321 has 2 divisors, whose sum is σ = 721402322. Its totient is φ = 721402320.

The previous prime is 721402313. The next prime is 721402343. The reversal of 721402321 is 123204127.

It is an a-pointer prime, because the next prime (721402343) can be obtained adding 721402321 to its sum of digits (22).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 487923921 + 233478400 = 22089^2 + 15280^2 .

It is an emirp because it is prime and its reverse (123204127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721402321 - 2³ = 721402313 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 721402292 and 721402301.

It is not a weakly prime, because it can be changed into another prime (721402301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360701160 + 360701161.

It is an arithmetic number, because the mean of its divisors is an integer number (360701161).

Almost surely, 2^721402321 is an apocalyptic number.

It is an amenable number.

721402321 is a deficient number, since it is larger than the sum of its proper divisors (1).

721402321 is an equidigital number, since it uses as much as digits as its factorization.

721402321 is an evil number, because the sum of its binary digits is even.

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

The square root of 721402321 is about 26858.9337279051. The cubic root of 721402321 is about 896.8624578707.

Adding to 721402321 its reverse (123204127), we get a palindrome (844606448).

The spelling of 721402321 in words is "seven hundred twenty-one million, four hundred two thousand, three hundred twenty-one".