21861271 has 4 divisors (see below), whose sum is σ = 21930552. Its totient is φ = 21791992.

The previous prime is 21861263. The next prime is 21861283. The reversal of 21861271 is 17216812.

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 21861271 - 2³ = 21861263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21861221) 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, 34165 + ... + 34798.

It is an arithmetic number, because the mean of its divisors is an integer number (5482638).

Almost surely, 2^21861271 is an apocalyptic number.

21861271 is a deficient number, since it is larger than the sum of its proper divisors (69281).

21861271 is an equidigital number, since it uses as much as digits as its factorization.

21861271 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69280.

The product of its digits is 1344, while the sum is 28.

The square root of 21861271 is about 4675.6038112740. The cubic root of 21861271 is about 279.6137147788.

The spelling of 21861271 in words is "twenty-one million, eight hundred sixty-one thousand, two hundred seventy-one".