21026880 has 252 divisors, whose sum is σ = 84696300. Its totient is φ = 4773888.

The previous prime is 21026869. The next prime is 21026881. The reversal of 21026880 is 8862012.

It can be written as a sum of positive squares in 2 ways, for example, as 4769856 + 16257024 = 2184^2 + 4032^2 .

It is a tau number, because it is divible by the number of its divisors (252).

It is a super-3 number, since 3×21026880³ (a number of 23 digits) contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (21026881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 141046 + ... + 141194.

Almost surely, 2^21026880 is an apocalyptic number.

21026880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21026880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42348150).

21026880 is an abundant number, since it is smaller than the sum of its proper divisors (63669420).

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

21026880 is a wasteful number, since it uses less digits than its factorization.

21026880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186 (or 166 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 27.

The square root of 21026880 is about 4585.5076054893. The cubic root of 21026880 is about 276.0100815473.

Adding to 21026880 its reverse (8862012), we get a palindrome (29888892).

The spelling of 21026880 in words is "twenty-one million, twenty-six thousand, eight hundred eighty".