10001221020 has 144 divisors (see below), whose sum is σ = 35516714688. Its totient is φ = 2230225920.

The previous prime is 10001221019. The next prime is 10001221081. The reversal of 10001221020 is 2012210001.

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 = 10001220993 and 10001221011.

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, 45139 + ... + 148458.

It is an arithmetic number, because the mean of its divisors is an integer number (246643852).

Almost surely, 2^10001221020 is an apocalyptic number.

10001221020 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

10001221020 is an abundant number, since it is smaller than the sum of its proper divisors (25515493668).

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

10001221020 is a wasteful number, since it uses less digits than its factorization.

10001221020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193660 (or 193655 counting only the distinct ones).

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

Adding to 10001221020 its reverse (2012210001), we get a palindrome (12013431021).

The spelling of 10001221020 in words is "ten billion, one million, two hundred twenty-one thousand, twenty".