2121000021 has 12 divisors (see below), whose sum is σ = 3501333472. Its totient is φ = 1211999976.

The previous prime is 2120999989. The next prime is 2121000023. The reversal of 2121000021 is 1200001212.

It is not a de Polignac number, because 2121000021 - 2⁵ = 2120999989 is a prime.

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 = 2120999967 and 2121000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121000023) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 16833271 + ... + 16833396.

Almost surely, 2^2121000021 is an apocalyptic number.

2121000021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2121000021 is a deficient number, since it is larger than the sum of its proper divisors (1380333451).

2121000021 is a wasteful number, since it uses less digits than its factorization.

2121000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33666680 (or 33666677 counting only the distinct ones).

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

The square root of 2121000021 is about 46054.3159866695. The cubic root of 2121000021 is about 1284.8336163120.

Adding to 2121000021 its reverse (1200001212), we get a palindrome (3321001233).

The spelling of 2121000021 in words is "two billion, one hundred twenty-one million, twenty-one", and thus it is an aban number.