21871172 has 12 divisors (see below), whose sum is σ = 38669820. Its totient is φ = 10822656.

The previous prime is 21871169. The next prime is 21871207. The reversal of 21871172 is 27117812.

It can be written as a sum of positive squares in 2 ways, for example, as 4946176 + 16924996 = 2224^2 + 4114^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27797 + ... + 28572.

It is an arithmetic number, because the mean of its divisors is an integer number (3222485).

Almost surely, 2^21871172 is an apocalyptic number.

It is an amenable number.

21871172 is a deficient number, since it is larger than the sum of its proper divisors (16798648).

21871172 is a wasteful number, since it uses less digits than its factorization.

21871172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56470 (or 56468 counting only the distinct ones).

The product of its digits is 1568, while the sum is 29.

The square root of 21871172 is about 4676.6624851490. The cubic root of 21871172 is about 279.6559208876.

Adding to 21871172 its reverse (27117812), we get a palindrome (48988984).

The spelling of 21871172 in words is "twenty-one million, eight hundred seventy-one thousand, one hundred seventy-two".