2021000100021 has 24 divisors (see below), whose sum is σ = 3381956252480. Its totient is φ = 1139037235776.

The previous prime is 2021000100017. The next prime is 2021000100043. The reversal of 2021000100021 is 1200010001202.

It is not a de Polignac number, because 2021000100021 - 2² = 2021000100017 is a prime.

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

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2021000099976 and 2021000100012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021000100001) 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, 219717091 + ... + 219726288.

Almost surely, 2^{2021000100021} is an apocalyptic number.

2021000100021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

2021000100021 is a deficient number, since it is larger than the sum of its proper divisors (1360956152459).

2021000100021 is a wasteful number, since it uses less digits than its factorization.

2021000100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439443465 (or 439443462 counting only the distinct ones).

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

Adding to 2021000100021 its reverse (1200010001202), we get a palindrome (3221010101223).

The spelling of 2021000100021 in words is "two trillion, twenty-one billion, one hundred thousand, twenty-one".