21064571 has 4 divisors (see below), whose sum is σ = 22979544. Its totient is φ = 19149600.

The previous prime is 21064567. The next prime is 21064579. The reversal of 21064571 is 17546012.

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 21064571 - 2² = 21064567 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21064571.

It is not an unprimeable number, because it can be changed into a prime (21064579) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 957470 + ... + 957491.

It is an arithmetic number, because the mean of its divisors is an integer number (5744886).

Almost surely, 2^21064571 is an apocalyptic number.

21064571 is a deficient number, since it is larger than the sum of its proper divisors (1914973).

21064571 is a wasteful number, since it uses less digits than its factorization.

21064571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1914972.

The product of its (nonzero) digits is 1680, while the sum is 26.

The square root of 21064571 is about 4589.6155612426. The cubic root of 21064571 is about 276.1749005197.

The spelling of 21064571 in words is "twenty-one million, sixty-four thousand, five hundred seventy-one".