21036571 has 4 divisors (see below), whose sum is σ = 21762000. Its totient is φ = 20311144.

The previous prime is 21036563. The next prime is 21036577. The reversal of 21036571 is 17563012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21036571 - 2³ = 21036563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21036577) 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 in 3 ways as a sum of consecutive naturals, for example, 362671 + ... + 362728.

It is an arithmetic number, because the mean of its divisors is an integer number (5440500).

Almost surely, 2^21036571 is an apocalyptic number.

21036571 is a deficient number, since it is larger than the sum of its proper divisors (725429).

21036571 is an equidigital number, since it uses as much as digits as its factorization.

21036571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725428.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21036571 is about 4586.5641824791. The cubic root of 21036571 is about 276.0524781190.

Adding to 21036571 its reverse (17563012), we get a palindrome (38599583).

The spelling of 21036571 in words is "twenty-one million, thirty-six thousand, five hundred seventy-one".