21880 has 16 divisors (see below), whose sum is σ = 49320. Its totient is φ = 8736.

The previous prime is 21871. The next prime is 21881. The reversal of 21880 is 8812.

21880 = T₁₁ + T₁₂ + ... + T₅₀.

It is a happy number.

21880 is nontrivially palindromic in base 3.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21881) by changing a digit.

21880 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 234 + ... + 313.

2²¹⁸⁸⁰ is an apocalyptic number.

21880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21880 is an abundant number, since it is smaller than the sum of its proper divisors (27440).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24660).

21880 is a wasteful number, since it uses less digits than its factorization.

21880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 558 (or 554 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21880 is about 147.9188966968. The cubic root of 21880 is about 27.9693542258.

The spelling of 21880 in words is "twenty-one thousand, eight hundred eighty".