21666046 has 16 divisors (see below), whose sum is σ = 34020000. Its totient is φ = 10329088.

The previous prime is 21666037. The next prime is 21666049. The reversal of 21666046 is 64066612.

It is a junction number, because it is equal to n+sod(n) for n = 21665999 and 21666017.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666049) 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, 20130 + ... + 21178.

It is an arithmetic number, because the mean of its divisors is an integer number (2126250).

Almost surely, 2^21666046 is an apocalyptic number.

21666046 is a deficient number, since it is larger than the sum of its proper divisors (12353954).

21666046 is a wasteful number, since it uses less digits than its factorization.

21666046 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1523.

The product of its (nonzero) digits is 10368, while the sum is 31.

The square root of 21666046 is about 4654.6800104841. The cubic root of 21666046 is about 278.7788915471.

The spelling of 21666046 in words is "twenty-one million, six hundred sixty-six thousand, forty-six".