421721389 has 2 divisors, whose sum is σ = 421721390. Its totient is φ = 421721388.

The previous prime is 421721309. The next prime is 421721401. The reversal of 421721389 is 983127124.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 348755625 + 72965764 = 18675^2 + 8542^2 .

It is a cyclic number.

It is not a de Polignac number, because 421721389 - 2¹¹ = 421719341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421721309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210860694 + 210860695.

It is an arithmetic number, because the mean of its divisors is an integer number (210860695).

Almost surely, 2^421721389 is an apocalyptic number.

It is an amenable number.

421721389 is a deficient number, since it is larger than the sum of its proper divisors (1).

421721389 is an equidigital number, since it uses as much as digits as its factorization.

421721389 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 37.

The square root of 421721389 is about 20535.8561788887. The cubic root of 421721389 is about 749.9089602087.

The spelling of 421721389 in words is "four hundred twenty-one million, seven hundred twenty-one thousand, three hundred eighty-nine".