21550166 has 8 divisors (see below), whose sum is σ = 35263944. Its totient is φ = 9795520.

The previous prime is 21550157. The next prime is 21550183. The reversal of 21550166 is 66105512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489755 + ... + 489798.

It is an arithmetic number, because the mean of its divisors is an integer number (4407993).

Almost surely, 2^21550166 is an apocalyptic number.

21550166 is a deficient number, since it is larger than the sum of its proper divisors (13713778).

21550166 is a wasteful number, since it uses less digits than its factorization.

21550166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 979566.

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21550166 is about 4642.2156348020. The cubic root of 21550166 is about 278.2809901530.

Adding to 21550166 its reverse (66105512), we get a palindrome (87655678).

It can be divided in two parts, 215 and 50166, that multiplied together give a triangular number (10785690 = T₄₆₄₄).

The spelling of 21550166 in words is "twenty-one million, five hundred fifty thousand, one hundred sixty-six".