2021011220021 has 4 divisors (see below), whose sum is σ = 2022916038444. Its totient is φ = 2019106401600.

The previous prime is 2021011220017. The next prime is 2021011220023. The reversal of 2021011220021 is 1200221101202.

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 430448839396 + 1590562380625 = 656086^2 + 1261175^2 .

It is a cyclic number.

It is not a de Polignac number, because 2021011220021 - 2² = 2021011220017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2021011219978 and 2021011220005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2021011220023) 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, 952407620 + ... + 952409741.

It is an arithmetic number, because the mean of its divisors is an integer number (505729009611).

Almost surely, 2^{2021011220021} is an apocalyptic number.

It is an amenable number.

2021011220021 is a deficient number, since it is larger than the sum of its proper divisors (1904818423).

2021011220021 is a wasteful number, since it uses less digits than its factorization.

2021011220021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1904818422.

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 2021011220021 its reverse (1200221101202), we get a palindrome (3221232321223).

The spelling of 2021011220021 in words is "two trillion, twenty-one billion, eleven million, two hundred twenty thousand, twenty-one".