20421100020100 has 216 divisors, whose sum is σ = 50509538823240. Its totient is φ = 7122957557760.

The previous prime is 20421100020017. The next prime is 20421100020149. The reversal of 20421100020100 is 102000112402.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 7643720913984 + 12777379106116 = 2764728^2 + 3574546^2 .

It is a Harshad number since it is a multiple of its sum of digits (13).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 165601266 + ... + 165724534.

It is an arithmetic number, because the mean of its divisors is an integer number (233840457515).

Almost surely, 2^{20421100020100} is an apocalyptic number.

20421100020100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20421100020100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25254769411620).

20421100020100 is an abundant number, since it is smaller than the sum of its proper divisors (30088438803140).

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

20421100020100 is a wasteful number, since it uses less digits than its factorization.

20421100020100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123687 (or 123661 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

Adding to 20421100020100 its reverse (102000112402), we get a palindrome (20523100132502).

The spelling of 20421100020100 in words is "twenty trillion, four hundred twenty-one billion, one hundred million, twenty thousand, one hundred".