21686266 has 16 divisors (see below), whose sum is σ = 37472256. Its totient is φ = 9220176.

The previous prime is 21686257. The next prime is 21686279. The reversal of 21686266 is 66268612.

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, 4321 + ... + 7876.

It is an arithmetic number, because the mean of its divisors is an integer number (2342016).

Almost surely, 2^21686266 is an apocalyptic number.

21686266 is a deficient number, since it is larger than the sum of its proper divisors (15785990).

21686266 is a wasteful number, since it uses less digits than its factorization.

21686266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12333.

The product of its digits is 41472, while the sum is 37.

The square root of 21686266 is about 4656.8515114828. The cubic root of 21686266 is about 278.8655887466.

It can be divided in two parts, 21686 and 266, that added together give a cube (21952 = 28³).

The spelling of 21686266 in words is "twenty-one million, six hundred eighty-six thousand, two hundred sixty-six".