990121112021 has 4 divisors (see below), whose sum is σ = 991276446732. Its totient is φ = 988965777312.

The previous prime is 990121112011. The next prime is 990121112111. The reversal of 990121112021 is 120211121099.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 957941775025 + 32179336996 = 978745^2 + 179386^2 .

It is a cyclic number.

It is not a de Polignac number, because 990121112021 - 2¹⁰ = 990121110997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (990121112011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 577666070 + ... + 577667783.

It is an arithmetic number, because the mean of its divisors is an integer number (247819111683).

Almost surely, 2^990121112021 is an apocalyptic number.

It is an amenable number.

990121112021 is a deficient number, since it is larger than the sum of its proper divisors (1155334711).

990121112021 is a wasteful number, since it uses less digits than its factorization.

990121112021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1155334710.

The product of its (nonzero) digits is 648, while the sum is 29.

The spelling of 990121112021 in words is "nine hundred ninety billion, one hundred twenty-one million, one hundred twelve thousand, twenty-one".