21866071 has 4 divisors (see below), whose sum is σ = 21884472. Its totient is φ = 21847672.

The previous prime is 21866069. The next prime is 21866081. The reversal of 21866071 is 17066812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21866071 - 2¹ = 21866069 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21866011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7285 + ... + 9838.

It is an arithmetic number, because the mean of its divisors is an integer number (5471118).

Almost surely, 2^21866071 is an apocalyptic number.

21866071 is a deficient number, since it is larger than the sum of its proper divisors (18401).

21866071 is a wasteful number, since it uses less digits than its factorization.

21866071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18400.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 21866071 is about 4676.1170857882. The cubic root of 21866071 is about 279.6341778710.

The spelling of 21866071 in words is "twenty-one million, eight hundred sixty-six thousand, seventy-one".