2100021021 has 12 divisors (see below), whose sum is σ = 3466701472. Its totient is φ = 1200011976.

The previous prime is 2100021013. The next prime is 2100021029. The reversal of 2100021021 is 1201200012.

It is an interprime number because it is at equal distance from previous prime (2100021013) and next prime (2100021029).

It is not a de Polignac number, because 2100021021 - 2³ = 2100021013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

2100021021 is a modest number, since divided by 21021 gives 2100 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 2100020994 and 2100021012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2100021029) 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, 16666771 + ... + 16666896.

Almost surely, 2^2100021021 is an apocalyptic number.

2100021021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2100021021 is a deficient number, since it is larger than the sum of its proper divisors (1366680451).

2100021021 is a wasteful number, since it uses less digits than its factorization.

2100021021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33333680 (or 33333677 counting only the distinct ones).

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

The square root of 2100021021 is about 45825.9863068980. The cubic root of 2100021021 is about 1280.5834378391.

Adding to 2100021021 its reverse (1201200012), we get a palindrome (3301221033).

The spelling of 2100021021 in words is "two billion, one hundred million, twenty-one thousand, twenty-one".