21202666 has 8 divisors (see below), whose sum is σ = 31854240. Its totient is φ = 10584588.

The previous prime is 21202663. The next prime is 21202669. The reversal of 21202666 is 66620212.

It is an interprime number because it is at equal distance from previous prime (21202663) and next prime (21202669).

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

It is a self number, because there is not a number n which added to its sum of digits gives 21202666.

It is not an unprimeable number, because it can be changed into a prime (21202663) 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, 6726 + ... + 9361.

It is an arithmetic number, because the mean of its divisors is an integer number (3981780).

Almost surely, 2^21202666 is an apocalyptic number.

21202666 is a deficient number, since it is larger than the sum of its proper divisors (10651574).

21202666 is a wasteful number, since it uses less digits than its factorization.

21202666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16748.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 21202666 is about 4604.6352732871. The cubic root of 21202666 is about 276.7771017650. Note that the first 3 decimals are identical.

Adding to 21202666 its reverse (66620212), we get a palindrome (87822878).

The spelling of 21202666 in words is "twenty-one million, two hundred two thousand, six hundred sixty-six".