21166280 has 16 divisors (see below), whose sum is σ = 47624220. Its totient is φ = 8466496.

The previous prime is 21166253. The next prime is 21166283. The reversal of 21166280 is 8266112.

It can be written as a sum of positive squares in 2 ways, for example, as 19166884 + 1999396 = 4378^2 + 1414^2 .

It is a super-2 number, since 2×21166280² = 896022818076800, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21166283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264539 + ... + 264618.

Almost surely, 2^21166280 is an apocalyptic number.

21166280 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21166280 is an abundant number, since it is smaller than the sum of its proper divisors (26457940).

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

21166280 is a wasteful number, since it uses less digits than its factorization.

21166280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 529168 (or 529164 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 21166280 is about 4600.6825580559. The cubic root of 21166280 is about 276.6186849260.

The spelling of 21166280 in words is "twenty-one million, one hundred sixty-six thousand, two hundred eighty".