21001020011021 has 4 divisors (see below), whose sum is σ = 21568615146492. Its totient is φ = 20433424875552.

The previous prime is 21001020011003. The next prime is 21001020011039. The reversal of 21001020011021 is 12011002010012.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21001020011003) and next prime (21001020011039).

It can be written as a sum of positive squares in 2 ways, for example, as 15497913954121 + 5503106056900 = 3936739^2 + 2345870^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21001020011021 is a prime.

It is a super-2 number, since 2×21001020011021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21001020010993 and 21001020011011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21001020011221) 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, 283797567680 + ... + 283797567753.

It is an arithmetic number, because the mean of its divisors is an integer number (5392153786623).

Almost surely, 2^{21001020011021} is an apocalyptic number.

It is an amenable number.

21001020011021 is a deficient number, since it is larger than the sum of its proper divisors (567595135471).

21001020011021 is an equidigital number, since it uses as much as digits as its factorization.

21001020011021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567595135470.

The product of its (nonzero) digits is 8, while the sum is 11.

Adding to 21001020011021 its reverse (12011002010012), we get a palindrome (33012022021033).

The spelling of 21001020011021 in words is "twenty-one trillion, one billion, twenty million, eleven thousand, twenty-one".