21895666 has 8 divisors (see below), whose sum is σ = 35369964. Its totient is φ = 10105680.

The previous prime is 21895663. The next prime is 21895669. The reversal of 21895666 is 66659812.

It is an interprime number because it is at equal distance from previous prime (21895663) and next prime (21895669).

It can be written as a sum of positive squares in 2 ways, for example, as 20385225 + 1510441 = 4515^2 + 1229^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21895661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 421045 + ... + 421096.

Almost surely, 2^21895666 is an apocalyptic number.

21895666 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21895666 is a deficient number, since it is larger than the sum of its proper divisors (13474298).

21895666 is a wasteful number, since it uses less digits than its factorization.

21895666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 842156.

The product of its digits is 155520, while the sum is 43.

The square root of 21895666 is about 4679.2805002479. The cubic root of 21895666 is about 279.7602795171.

The spelling of 21895666 in words is "twenty-one million, eight hundred ninety-five thousand, six hundred sixty-six".