421642021 has 2 divisors, whose sum is σ = 421642022. Its totient is φ = 421642020.

The previous prime is 421641989. The next prime is 421642037. The reversal of 421642021 is 120246124.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 420701121 + 940900 = 20511^2 + 970^2 .

It is a cyclic number.

It is not a de Polignac number, because 421642021 - 2⁵ = 421641989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 421641983 and 421642001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (421642051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210821010 + 210821011.

It is an arithmetic number, because the mean of its divisors is an integer number (210821011).

Almost surely, 2^421642021 is an apocalyptic number.

It is an amenable number.

421642021 is a deficient number, since it is larger than the sum of its proper divisors (1).

421642021 is an equidigital number, since it uses as much as digits as its factorization.

421642021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 421642021 is about 20533.9236630509. The cubic root of 421642021 is about 749.8619129479.

Adding to 421642021 its reverse (120246124), we get a palindrome (541888145).

The spelling of 421642021 in words is "four hundred twenty-one million, six hundred forty-two thousand, twenty-one".