21866061 has 8 divisors (see below), whose sum is σ = 33319744. Its totient is φ = 12494880.

The previous prime is 21866057. The next prime is 21866069. The reversal of 21866061 is 16066812.

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

It is not a de Polignac number, because 21866061 - 2² = 21866057 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 (21866069) 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 7 ways as a sum of consecutive naturals, for example, 520600 + ... + 520641.

It is an arithmetic number, because the mean of its divisors is an integer number (4164968).

Almost surely, 2^21866061 is an apocalyptic number.

21866061 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21866061 is a deficient number, since it is larger than the sum of its proper divisors (11453683).

21866061 is a wasteful number, since it uses less digits than its factorization.

21866061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1041251.

The product of its (nonzero) digits is 3456, while the sum is 30.

The square root of 21866061 is about 4676.1160165248. The cubic root of 21866061 is about 279.6341352427.

The spelling of 21866061 in words is "twenty-one million, eight hundred sixty-six thousand, sixty-one".