1020121999956 has 144 divisors (see below), whose sum is σ = 2770465593168. Its totient is φ = 315342028800.

The previous prime is 1020121999933. The next prime is 1020122000057. The reversal of 1020121999956 is 6599991210201.

It can be written as a sum of positive squares in 8 ways, for example, as 72945367056 + 947176632900 = 270084^2 + 973230^2 .

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, 47390476 + ... + 47411996.

It is an arithmetic number, because the mean of its divisors is an integer number (19239344397).

Almost surely, 2^{1020121999956} 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 1020121999956, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1385232796584).

1020121999956 is an abundant number, since it is smaller than the sum of its proper divisors (1750343593212).

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

1020121999956 is a wasteful number, since it uses less digits than its factorization.

1020121999956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22682 (or 22677 counting only the distinct ones).

The product of its (nonzero) digits is 787320, while the sum is 54.

The spelling of 1020121999956 in words is "one trillion, twenty billion, one hundred twenty-one million, nine hundred ninety-nine thousand, nine hundred fifty-six".