21101886 has 48 divisors (see below), whose sum is σ = 50843520. Its totient is φ = 6281280.

The previous prime is 21101869. The next prime is 21101887. The reversal of 21101886 is 68810112.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101887) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5800 + ... + 8708.

It is an arithmetic number, because the mean of its divisors is an integer number (1059240).

Almost surely, 2^21101886 is an apocalyptic number.

21101886 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 21101886, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25421760).

21101886 is an abundant number, since it is smaller than the sum of its proper divisors (29741634).

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

21101886 is a wasteful number, since it uses less digits than its factorization.

21101886 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2961 (or 2958 counting only the distinct ones).

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

The square root of 21101886 is about 4593.6789178174. The cubic root of 21101886 is about 276.3378817195.

Adding to 21101886 its reverse (68810112), we get a palindrome (89911998).

The spelling of 21101886 in words is "twenty-one million, one hundred one thousand, eight hundred eighty-six".