21666463 has 8 divisors (see below), whose sum is σ = 26666528. Its totient is φ = 17142624.

The previous prime is 21666443. The next prime is 21666481. The reversal of 21666463 is 36466612.

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

It is a cyclic number.

It is not a de Polignac number, because 21666463 - 2⁹ = 21665951 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666443) 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, 118956 + ... + 119137.

It is an arithmetic number, because the mean of its divisors is an integer number (3333316).

Almost surely, 2^21666463 is an apocalyptic number.

21666463 is a deficient number, since it is larger than the sum of its proper divisors (5000065).

21666463 is a wasteful number, since it uses less digits than its factorization.

21666463 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 238113.

The product of its digits is 31104, while the sum is 34.

The square root of 21666463 is about 4654.7248038955. The cubic root of 21666463 is about 278.7806800607.

The spelling of 21666463 in words is "twenty-one million, six hundred sixty-six thousand, four hundred sixty-three".