21351866 has 8 divisors (see below), whose sum is σ = 33420384. Its totient is φ = 10211740.

The previous prime is 21351829. The next prime is 21351893. The reversal of 21351866 is 66815312.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 232040 + ... + 232131.

It is an arithmetic number, because the mean of its divisors is an integer number (4177548).

Almost surely, 2^21351866 is an apocalyptic number.

21351866 is a deficient number, since it is larger than the sum of its proper divisors (12068518).

21351866 is a wasteful number, since it uses less digits than its factorization.

21351866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 464196.

The product of its digits is 8640, while the sum is 32.

The square root of 21351866 is about 4620.8079380126. The cubic root of 21351866 is about 277.4247979541.

The spelling of 21351866 in words is "twenty-one million, three hundred fifty-one thousand, eight hundred sixty-six".