21983666 has 4 divisors (see below), whose sum is σ = 32975502. Its totient is φ = 10991832.

The previous prime is 21983641. The next prime is 21983671. The reversal of 21983666 is 66638912.

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., 16362025 + 5621641 = 4045^2 + 2371^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5495915 + ... + 5495918.

Almost surely, 2^21983666 is an apocalyptic number.

21983666 is a deficient number, since it is larger than the sum of its proper divisors (10991836).

21983666 is a wasteful number, since it uses less digits than its factorization.

21983666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10991835.

The product of its digits is 93312, while the sum is 41.

The square root of 21983666 is about 4688.6742262606. The cubic root of 21983666 is about 280.1345696684.

The spelling of 21983666 in words is "twenty-one million, nine hundred eighty-three thousand, six hundred sixty-six".