21166056 has 128 divisors (see below), whose sum is σ = 63360000. Its totient is φ = 6531840.

The previous prime is 21166051. The next prime is 21166099. The reversal of 21166056 is 65066112.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21166051) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 194130 + ... + 194238.

It is an arithmetic number, because the mean of its divisors is an integer number (495000).

Almost surely, 2^21166056 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21166056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31680000).

21166056 is an abundant number, since it is smaller than the sum of its proper divisors (42193944).

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

21166056 is a wasteful number, since it uses less digits than its factorization.

21166056 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184 (or 174 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 27.

The square root of 21166056 is about 4600.6582137777. The cubic root of 21166056 is about 276.6177091160.

The spelling of 21166056 in words is "twenty-one million, one hundred sixty-six thousand, fifty-six".