20511105210 has 96 divisors (see below), whose sum is σ = 55221089040. Its totient is φ = 5275920384.

The previous prime is 20511105191. The next prime is 20511105211. The reversal of 20511105210 is 1250111502.

It can be written as a sum of positive squares in 8 ways, for example, as 11376142281 + 9134962929 = 106659^2 + 95577^2 .

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

It is not an unprimeable number, because it can be changed into a prime (20511105211) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3225394 + ... + 3231746.

Almost surely, 2^20511105210 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20511105210, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27610544520).

20511105210 is an abundant number, since it is smaller than the sum of its proper divisors (34709983830).

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

20511105210 is a wasteful number, since it uses less digits than its factorization.

20511105210 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7632 (or 7629 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 18.

Adding to 20511105210 its reverse (1250111502), we get a palindrome (21761216712).

The spelling of 20511105210 in words is "twenty billion, five hundred eleven million, one hundred five thousand, two hundred ten".