21106554 has 96 divisors (see below), whose sum is σ = 53778816. Its totient is φ = 5483520.

The previous prime is 21106543. The next prime is 21106573. The reversal of 21106554 is 45560112.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 204867 + ... + 204969.

It is an arithmetic number, because the mean of its divisors is an integer number (560196).

Almost surely, 2^21106554 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21106554, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26889408).

21106554 is an abundant number, since it is smaller than the sum of its proper divisors (32672262).

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

21106554 is a wasteful number, since it uses less digits than its factorization.

21106554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 21106554 is about 4594.1869792162. The cubic root of 21106554 is about 276.3582566775.

Adding to 21106554 its reverse (45560112), we get a palindrome (66666666).

The spelling of 21106554 in words is "twenty-one million, one hundred six thousand, five hundred fifty-four".