21872166 has 16 divisors (see below), whose sum is σ = 46317744. Its totient is φ = 6861824.

The previous prime is 21872159. The next prime is 21872171. The reversal of 21872166 is 66127812.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 107115 + ... + 107318.

It is an arithmetic number, because the mean of its divisors is an integer number (2894859).

Almost surely, 2^21872166 is an apocalyptic number.

21872166 is an abundant number, since it is smaller than the sum of its proper divisors (24445578).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21872166 is a wasteful number, since it uses less digits than its factorization.

21872166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 214455.

The product of its digits is 8064, while the sum is 33.

The square root of 21872166 is about 4676.7687563103. The cubic root of 21872166 is about 279.6601574198.

Adding to 21872166 its reverse (66127812), we get a palindrome (87999978).

The spelling of 21872166 in words is "twenty-one million, eight hundred seventy-two thousand, one hundred sixty-six".