2021121009 has 12 divisors (see below), whose sum is σ = 2930253300. Its totient is φ = 1342403424.

The previous prime is 2021120989. The next prime is 2021121017. The reversal of 2021121009 is 9001211202.

It can be written as a sum of positive squares in 2 ways, for example, as 315843984 + 1705277025 = 17772^2 + 41295^2 .

It is not a de Polignac number, because 2021121009 - 2¹¹ = 2021118961 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 2021120982 and 2021121000.

It is not an unprimeable number, because it can be changed into a prime (2021121209) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 414994 + ... + 419835.

It is an arithmetic number, because the mean of its divisors is an integer number (244187775).

Almost surely, 2^2021121009 is an apocalyptic number.

It is an amenable number.

2021121009 is a deficient number, since it is larger than the sum of its proper divisors (909132291).

2021121009 is a wasteful number, since it uses less digits than its factorization.

2021121009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 835104 (or 835101 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 2021121009 is about 44956.8794401925. The cubic root of 2021121009 is about 1264.3406624071.

It can be divided in two parts, 202 and 1121009, that added together give a palindrome (1121211).

The spelling of 2021121009 in words is "two billion, twenty-one million, one hundred twenty-one thousand, nine".