21666147 has 8 divisors (see below), whose sum is σ = 29295360. Its totient is φ = 14240520.

The previous prime is 21666121. The next prime is 21666149. The reversal of 21666147 is 74166612.

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

It is not a de Polignac number, because 21666147 - 2⁶ = 21666083 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21666149) 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, 50647 + ... + 51072.

It is an arithmetic number, because the mean of its divisors is an integer number (3661920).

Almost surely, 2^21666147 is an apocalyptic number.

21666147 is a deficient number, since it is larger than the sum of its proper divisors (7629213).

21666147 is a wasteful number, since it uses less digits than its factorization.

21666147 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 101793.

The product of its digits is 12096, while the sum is 33.

The square root of 21666147 is about 4654.6908597672. The cubic root of 21666147 is about 278.7793247384.

The spelling of 21666147 in words is "twenty-one million, six hundred sixty-six thousand, one hundred forty-seven".