21821071 has 2 divisors, whose sum is σ = 21821072. Its totient is φ = 21821070.

The previous prime is 21821039. The next prime is 21821119. The reversal of 21821071 is 17012812.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21821071 - 2⁵ = 21821039 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 (21821171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10910535 + 10910536.

It is an arithmetic number, because the mean of its divisors is an integer number (10910536).

Almost surely, 2^21821071 is an apocalyptic number.

21821071 is a deficient number, since it is larger than the sum of its proper divisors (1).

21821071 is an equidigital number, since it uses as much as digits as its factorization.

21821071 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 22.

The square root of 21821071 is about 4671.3029231682. The cubic root of 21821071 is about 279.4422186766.

Adding to 21821071 its reverse (17012812), we get a palindrome (38833883).

The spelling of 21821071 in words is "twenty-one million, eight hundred twenty-one thousand, seventy-one".