21166530 has 192 divisors, whose sum is σ = 68947200. Its totient is φ = 4139520.

The previous prime is 21166529. The next prime is 21166559. The reversal of 21166530 is 3566112.

It is a self number, because there is not a number n which added to its sum of digits gives 21166530.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1245082 + ... + 1245098.

It is an arithmetic number, because the mean of its divisors is an integer number (359100).

Almost surely, 2^21166530 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21166530, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34473600).

21166530 is an abundant number, since it is smaller than the sum of its proper divisors (47780670).

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

21166530 is a wasteful number, since it uses less digits than its factorization.

21166530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 45 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21166530 is about 4600.7097278572. The cubic root of 21166530 is about 276.6197739915.

It can be divided in two parts, 2116 and 6530, that added together give a triangular number (8646 = T₁₃₁).

The spelling of 21166530 in words is "twenty-one million, one hundred sixty-six thousand, five hundred thirty".