21101001210 has 96 divisors (see below), whose sum is σ = 56486785680. Its totient is φ = 5461115904.

The previous prime is 21101001197. The next prime is 21101001253. The reversal of 21101001210 is 1210010112.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 12973437801 + 8127563409 = 113901^2 + 90153^2 .

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a junction number, because it is equal to n+sod(n) for n = 21101001192 and 21101001201.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1354224 + ... + 1369716.

Almost surely, 2^21101001210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21101001210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28243392840).

21101001210 is an abundant number, since it is smaller than the sum of its proper divisors (35385784470).

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

21101001210 is a wasteful number, since it uses less digits than its factorization.

21101001210 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15952 (or 15949 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21101001210 its reverse (1210010112), we get a palindrome (22311011322).

The spelling of 21101001210 in words is "twenty-one billion, one hundred one million, one thousand, two hundred ten".