21660266 has 16 divisors (see below), whose sum is σ = 34292160. Its totient is φ = 10232640.

The previous prime is 21660263. The next prime is 21660269. The reversal of 21660266 is 66206612.

It is an interprime number because it is at equal distance from previous prime (21660263) and next prime (21660269).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21660263) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24146 + ... + 25026.

It is an arithmetic number, because the mean of its divisors is an integer number (2143260).

Almost surely, 2^21660266 is an apocalyptic number.

21660266 is a deficient number, since it is larger than the sum of its proper divisors (12631894).

21660266 is a wasteful number, since it uses less digits than its factorization.

21660266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1549.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 21660266 is about 4654.0590885806. The cubic root of 21660266 is about 278.7540987553.

Adding to 21660266 its reverse (66206612), we get a palindrome (87866878).

The spelling of 21660266 in words is "twenty-one million, six hundred sixty thousand, two hundred sixty-six".