21168810 has 128 divisors (see below), whose sum is σ = 62818560. Its totient is φ = 5038848.

The previous prime is 21168803. The next prime is 21168817. The reversal of 21168810 is 1886112.

It is an interprime number because it is at equal distance from previous prime (21168803) and next prime (21168817).

It is a super-2 number, since 2×21168810² = 896237033632200, which contains 22 as substring.

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 (21168817) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 129789 + ... + 129951.

It is an arithmetic number, because the mean of its divisors is an integer number (490770).

Almost surely, 2^21168810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21168810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31409280).

21168810 is an abundant number, since it is smaller than the sum of its proper divisors (41649750).

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

21168810 is a wasteful number, since it uses less digits than its factorization.

21168810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 229 (or 223 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 21168810 is about 4600.9575090409. The cubic root of 21168810 is about 276.6297058736.

The spelling of 21168810 in words is "twenty-one million, one hundred sixty-eight thousand, eight hundred ten".