2101020021 has 24 divisors (see below), whose sum is σ = 3215407104. Its totient is φ = 1317432960.

The previous prime is 2101019993. The next prime is 2101020023. The reversal of 2101020021 is 1200201012.

It is a de Polignac number, because none of the positive numbers 2^k-2101020021 is a prime.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 2101019985 and 2101020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2101020023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 300556 + ... + 307466.

It is an arithmetic number, because the mean of its divisors is an integer number (133975296).

Almost surely, 2^2101020021 is an apocalyptic number.

It is an amenable number.

2101020021 is a deficient number, since it is larger than the sum of its proper divisors (1114387083).

2101020021 is a wasteful number, since it uses less digits than its factorization.

2101020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8921 (or 8918 counting only the distinct ones).

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

The square root of 2101020021 is about 45836.8849399695. The cubic root of 2101020021 is about 1280.7864675606.

Adding to 2101020021 its reverse (1200201012), we get a palindrome (3301221033).

The spelling of 2101020021 in words is "two billion, one hundred one million, twenty thousand, twenty-one".