21886666 has 4 divisors (see below), whose sum is σ = 32830002. Its totient is φ = 10943332.

The previous prime is 21886663. The next prime is 21886679. The reversal of 21886666 is 66668812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 21114025 + 772641 = 4595^2 + 879^2 .

It is a super-2 number, since 2×21886666² = 958052297191112, which contains 22 as substring.

21886666 is a modest number, since divided by 6666 gives 2188 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21886663) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5471665 + ... + 5471668.

Almost surely, 2^21886666 is an apocalyptic number.

21886666 is a deficient number, since it is larger than the sum of its proper divisors (10943336).

21886666 is a wasteful number, since it uses less digits than its factorization.

21886666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10943335.

The product of its digits is 165888, while the sum is 43.

The square root of 21886666 is about 4678.3187150941. The cubic root of 21886666 is about 279.7219433524.

The spelling of 21886666 in words is "twenty-one million, eight hundred eighty-six thousand, six hundred sixty-six".