21101010 has 64 divisors (see below), whose sum is σ = 58579200. Its totient is φ = 4764672.

The previous prime is 21100999. The next prime is 21101027. The reversal of 21101010 is 1010112.

It is a Harshad number since it is a multiple of its sum of digits (6).

It is a self number, because there is not a number n which added to its sum of digits gives 21101010.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18126 + ... + 19254.

It is an arithmetic number, because the mean of its divisors is an integer number (915300).

Almost surely, 2^21101010 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21101010, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29289600).

21101010 is an abundant number, since it is smaller than the sum of its proper divisors (37478190).

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

21101010 is a wasteful number, since it uses less digits than its factorization.

21101010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235.

The product of its (nonzero) digits is 2, while the sum is 6.

The square root of 21101010 is about 4593.5835684137. The cubic root of 21101010 is about 276.3340578064.

Adding to 21101010 its reverse (1010112), we get a palindrome (22111122).

The spelling of 21101010 in words is "twenty-one million, one hundred one thousand, ten".