20021100012 has 72 divisors (see below), whose sum is σ = 52270493184. Its totient is φ = 6458040576.

The previous prime is 20021099981. The next prime is 20021100019. The reversal of 20021100012 is 21000112002.

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 = 20021099967 and 20021100003.

It is not an unprimeable number, because it can be changed into a prime (20021100019) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 67413 + ... + 211155.

It is an arithmetic number, because the mean of its divisors is an integer number (725979072).

Almost surely, 2^20021100012 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20021100012, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26135246592).

20021100012 is an abundant number, since it is smaller than the sum of its proper divisors (32249393172).

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

20021100012 is a wasteful number, since it uses less digits than its factorization.

20021100012 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143879 (or 143874 counting only the distinct ones).

The product of its (nonzero) digits is 8, while the sum is 9.

Adding to 20021100012 its reverse (21000112002), we get a palindrome (41021212014).

The spelling of 20021100012 in words is "twenty billion, twenty-one million, one hundred thousand, twelve".