421340021 has 2 divisors, whose sum is σ = 421340022. Its totient is φ = 421340020.

The previous prime is 421340011. The next prime is 421340039. The reversal of 421340021 is 120043124.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 357739396 + 63600625 = 18914^2 + 7975^2 .

It is a cyclic number.

It is not a de Polignac number, because 421340021 - 2⁶ = 421339957 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421340011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210670010 + 210670011.

It is an arithmetic number, because the mean of its divisors is an integer number (210670011).

Almost surely, 2^421340021 is an apocalyptic number.

It is an amenable number.

421340021 is a deficient number, since it is larger than the sum of its proper divisors (1).

421340021 is an equidigital number, since it uses as much as digits as its factorization.

421340021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 421340021 is about 20526.5686611279. The cubic root of 421340021 is about 749.6828413068.

Adding to 421340021 its reverse (120043124), we get a palindrome (541383145).

The spelling of 421340021 in words is "four hundred twenty-one million, three hundred forty thousand, twenty-one".