20001002001021 has 12 divisors (see below), whose sum is σ = 28923128898300. Its totient is φ = 13318866253440.

The previous prime is 20001002001011. The next prime is 20001002001023. The reversal of 20001002001021 is 12010020010002.

It can be written as a sum of positive squares in 2 ways, for example, as 1226199660921 + 18774802340100 = 1107339^2 + 4332990^2 .

It is not a de Polignac number, because 20001002001021 - 2¹⁰ = 20001001999997 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 20001002000994 and 20001002001012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20001002001023) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1261248346 + ... + 1261264203.

It is an arithmetic number, because the mean of its divisors is an integer number (2410260741525).

Almost surely, 2^{20001002001021} is an apocalyptic number.

It is an amenable number.

20001002001021 is a deficient number, since it is larger than the sum of its proper divisors (8922126897279).

20001002001021 is a wasteful number, since it uses less digits than its factorization.

20001002001021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2522513436 (or 2522513433 counting only the distinct ones).

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

Adding to 20001002001021 its reverse (12010020010002), we get a palindrome (32011022011023).

The spelling of 20001002001021 in words is "twenty trillion, one billion, two million, one thousand, twenty-one".