21730266 has 12 divisors (see below), whose sum is σ = 47082282. Its totient is φ = 7243416.

The previous prime is 21730249. The next prime is 21730273. The reversal of 21730266 is 66203712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13727025 + 8003241 = 3705^2 + 2829^2 .

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a zygodrome in base 3.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 603601 + ... + 603636.

Almost surely, 2^21730266 is an apocalyptic number.

21730266 is an abundant number, since it is smaller than the sum of its proper divisors (25352016).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21730266 is a wasteful number, since it uses less digits than its factorization.

21730266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1207245 (or 1207242 counting only the distinct ones).

The product of its (nonzero) digits is 3024, while the sum is 27.

The square root of 21730266 is about 4661.5733395496. The cubic root of 21730266 is about 279.0540612856.

Adding to 21730266 its reverse (66203712), we get a palindrome (87933978).

The spelling of 21730266 in words is "twenty-one million, seven hundred thirty thousand, two hundred sixty-six".