21020271 has 4 divisors (see below), whose sum is σ = 28027032. Its totient is φ = 14013512.

The previous prime is 21020269. The next prime is 21020281. The reversal of 21020271 is 17202012.

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 21020271 - 2¹ = 21020269 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21020271.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020231) 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, 3503376 + ... + 3503381.

It is an arithmetic number, because the mean of its divisors is an integer number (7006758).

Almost surely, 2^21020271 is an apocalyptic number.

21020271 is a deficient number, since it is larger than the sum of its proper divisors (7006761).

21020271 is an equidigital number, since it uses as much as digits as its factorization.

21020271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7006760.

The product of its (nonzero) digits is 56, while the sum is 15.

The square root of 21020271 is about 4584.7869088977. The cubic root of 21020271 is about 275.9811607599.

Adding to 21020271 its reverse (17202012), we get a palindrome (38222283).

The spelling of 21020271 in words is "twenty-one million, twenty thousand, two hundred seventy-one".