21872871 has 12 divisors (see below), whose sum is σ = 31643248. Its totient is φ = 14559264.

The previous prime is 21872867. The next prime is 21872881. The reversal of 21872871 is 17827812.

It is a happy number.

It is not a de Polignac number, because 21872871 - 2² = 21872867 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 (21872801) 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 11 ways as a sum of consecutive naturals, for example, 5931 + ... + 8883.

Almost surely, 2^21872871 is an apocalyptic number.

21872871 is a deficient number, since it is larger than the sum of its proper divisors (9770377).

21872871 is a wasteful number, since it uses less digits than its factorization.

21872871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3782 (or 3779 counting only the distinct ones).

The product of its digits is 12544, while the sum is 36.

The square root of 21872871 is about 4676.8441282557. The cubic root of 21872871 is about 279.6631621260.

The spelling of 21872871 in words is "twenty-one million, eight hundred seventy-two thousand, eight hundred seventy-one".