21853571 has 2 divisors, whose sum is σ = 21853572. Its totient is φ = 21853570.

The previous prime is 21853561. The next prime is 21853603. The reversal of 21853571 is 17535812.

It is an a-pointer prime, because the next prime (21853603) can be obtained adding 21853571 to its sum of digits (32).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21853571 - 2¹⁰ = 21852547 is a prime.

It is not a weakly prime, because it can be changed into another prime (21853561) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10926785 + 10926786.

It is an arithmetic number, because the mean of its divisors is an integer number (10926786).

Almost surely, 2^21853571 is an apocalyptic number.

21853571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21853571 is an equidigital number, since it uses as much as digits as its factorization.

21853571 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8400, while the sum is 32.

The square root of 21853571 is about 4674.7803156940. The cubic root of 21853571 is about 279.5808823109.

The spelling of 21853571 in words is "twenty-one million, eight hundred fifty-three thousand, five hundred seventy-one".