21910 has 16 divisors (see below), whose sum is σ = 45216. Its totient is φ = 7488.

The previous prime is 21893. The next prime is 21911. The reversal of 21910 is 1912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21911) by changing a digit.

21910 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 7 ways as a sum of consecutive naturals, for example, 87 + ... + 226.

It is an arithmetic number, because the mean of its divisors is an integer number (2826).

2²¹⁹¹⁰ is an apocalyptic number.

21910 is an abundant number, since it is smaller than the sum of its proper divisors (23306).

It is a weird number, because it is abundant, but not a pseudoperfect number.

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22608).

21910 is a wasteful number, since it uses less digits than its factorization.

21910 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 327.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 21910 is about 148.0202688823. The cubic root of 21910 is about 27.9821314565.

It can be divided in two parts, 21 and 910, that multiplied together give a triangular number (19110 = T₁₉₅).

The spelling of 21910 in words is "twenty-one thousand, nine hundred ten".