2121001021 has 4 divisors (see below), whose sum is σ = 2122716892. Its totient is φ = 2119285152.

The previous prime is 2121001019. The next prime is 2121001031. The reversal of 2121001021 is 1201001212.

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 1764924121 + 356076900 = 42011^2 + 18870^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121001021 - 2¹ = 2121001019 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2121000989 and 2121001007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121001031) 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, 856080 + ... + 858553.

It is an arithmetic number, because the mean of its divisors is an integer number (530679223).

Almost surely, 2^2121001021 is an apocalyptic number.

It is an amenable number.

2121001021 is a deficient number, since it is larger than the sum of its proper divisors (1715871).

2121001021 is a wasteful number, since it uses less digits than its factorization.

2121001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1715870.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 2121001021 is about 46054.3268434140. The cubic root of 2121001021 is about 1284.8338182346.

Adding to 2121001021 its reverse (1201001212), we get a palindrome (3322002233).

The spelling of 2121001021 in words is "two billion, one hundred twenty-one million, one thousand, twenty-one".