100001221020 has 144 divisors (see below), whose sum is σ = 309276781632. Its totient is φ = 26149063680.

The previous prime is 100001220973. The next prime is 100001221037. The reversal of 100001221020 is 20122100001.

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 = 100001220993 and 100001221011.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2251225 + ... + 2295215.

It is an arithmetic number, because the mean of its divisors is an integer number (2147755428).

Almost surely, 2^100001221020 is an apocalyptic number.

100001221020 is a gapful number since it is divisible by the number (10) 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 100001221020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (154638390816).

100001221020 is an abundant number, since it is smaller than the sum of its proper divisors (209275560612).

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

100001221020 is a wasteful number, since it uses less digits than its factorization.

100001221020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44252 (or 44247 counting only the distinct ones).

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

Adding to 100001221020 its reverse (20122100001), we get a palindrome (120123321021).

The spelling of 100001221020 in words is "one hundred billion, one million, two hundred twenty-one thousand, twenty".