21871173 has 4 divisors (see below), whose sum is σ = 29161568. Its totient is φ = 14580780.

The previous prime is 21871169. The next prime is 21871207. The reversal of 21871173 is 37117812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21871173 - 2² = 21871169 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 21871173.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21871153) 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, 3645193 + ... + 3645198.

It is an arithmetic number, because the mean of its divisors is an integer number (7290392).

Almost surely, 2^21871173 is an apocalyptic number.

It is an amenable number.

21871173 is a deficient number, since it is larger than the sum of its proper divisors (7290395).

21871173 is an equidigital number, since it uses as much as digits as its factorization.

21871173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7290394.

The product of its digits is 2352, while the sum is 30.

The square root of 21871173 is about 4676.6625920628. The cubic root of 21871173 is about 279.6559251498.

Adding to 21871173 its reverse (37117812), we get a palindrome (58988985).

The spelling of 21871173 in words is "twenty-one million, eight hundred seventy-one thousand, one hundred seventy-three".