21866140 has 12 divisors (see below), whose sum is σ = 45918936. Its totient is φ = 8746448.

The previous prime is 21866137. The next prime is 21866189. The reversal of 21866140 is 4166812.

It is a junction number, because it is equal to n+sod(n) for n = 21866099 and 21866108.

It is a congruent number.

It is an unprimeable number.

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, 546634 + ... + 546673.

It is an arithmetic number, because the mean of its divisors is an integer number (3826578).

Almost surely, 2^21866140 is an apocalyptic number.

21866140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21866140 is an abundant number, since it is smaller than the sum of its proper divisors (24052796).

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

21866140 is a wasteful number, since it uses less digits than its factorization.

21866140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1093316 (or 1093314 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 21866140 is about 4676.1244636985. The cubic root of 21866140 is about 279.6344720061.

The spelling of 21866140 in words is "twenty-one million, eight hundred sixty-six thousand, one hundred forty".