21251002110 has 128 divisors (see below), whose sum is σ = 55728400896. Its totient is φ = 5154900480.

The previous prime is 21251002109. The next prime is 21251002117. The reversal of 21251002110 is 1120015212.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 21251002110.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251002117) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 20813400 + ... + 20814420.

It is an arithmetic number, because the mean of its divisors is an integer number (435378132).

Almost surely, 2^21251002110 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21251002110, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27864200448).

21251002110 is an abundant number, since it is smaller than the sum of its proper divisors (34477398786).

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

21251002110 is a wasteful number, since it uses less digits than its factorization.

21251002110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1770.

The product of its (nonzero) digits is 40, while the sum is 15.

Adding to 21251002110 its reverse (1120015212), we get a palindrome (22371017322).

The spelling of 21251002110 in words is "twenty-one billion, two hundred fifty-one million, two thousand, one hundred ten".