21142021 has 2 divisors, whose sum is σ = 21142022. Its totient is φ = 21142020.

The previous prime is 21141973. The next prime is 21142061. The reversal of 21142021 is 12024112.

It is a happy number.

21142021 is nontrivially palindromic in base 4.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18369796 + 2772225 = 4286^2 + 1665^2 .

It is a cyclic number.

It is not a de Polignac number, because 21142021 - 2⁷ = 21141893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21141992 and 21142010.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21142061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10571010 + 10571011.

It is an arithmetic number, because the mean of its divisors is an integer number (10571011).

Almost surely, 2^21142021 is an apocalyptic number.

It is an amenable number.

21142021 is a deficient number, since it is larger than the sum of its proper divisors (1).

21142021 is an equidigital number, since it uses as much as digits as its factorization.

21142021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21142021 is about 4598.0453455789. The cubic root of 21142021 is about 276.5129655463.

Adding to 21142021 its reverse (12024112), we get a palindrome (33166133).

The spelling of 21142021 in words is "twenty-one million, one hundred forty-two thousand, twenty-one".