21019571 has 2 divisors, whose sum is σ = 21019572. Its totient is φ = 21019570.

The previous prime is 21019549. The next prime is 21019597. The reversal of 21019571 is 17591012.

It is an a-pointer prime, because the next prime (21019597) can be obtained adding 21019571 to its sum of digits (26).

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21019571 - 2¹⁸ = 20757427 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21019571.

It is not a weakly prime, because it can be changed into another prime (21019541) 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, 10509785 + 10509786.

It is an arithmetic number, because the mean of its divisors is an integer number (10509786).

Almost surely, 2^21019571 is an apocalyptic number.

21019571 is a deficient number, since it is larger than the sum of its proper divisors (1).

21019571 is an equidigital number, since it uses as much as digits as its factorization.

21019571 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 630, while the sum is 26.

The square root of 21019571 is about 4584.7105688364. The cubic root of 21019571 is about 275.9780972257.

The spelling of 21019571 in words is "twenty-one million, nineteen thousand, five hundred seventy-one".