21256110 has 48 divisors (see below), whose sum is σ = 55826784. Its totient is φ = 5610816.

The previous prime is 21256099. The next prime is 21256129. The reversal of 21256110 is 1165212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a plaindrome in base 16.

It is a congruent number.

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 23 ways as a sum of consecutive naturals, for example, 8124 + ... + 10416.

It is an arithmetic number, because the mean of its divisors is an integer number (1163058).

Almost surely, 2^21256110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21256110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27913392).

21256110 is an abundant number, since it is smaller than the sum of its proper divisors (34570674).

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

21256110 is a wasteful number, since it uses less digits than its factorization.

21256110 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2409 (or 2406 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21256110 is about 4610.4349035639. The cubic root of 21256110 is about 277.0094572051.

The spelling of 21256110 in words is "twenty-one million, two hundred fifty-six thousand, one hundred ten".