102001020021 has 6 divisors (see below), whose sum is σ = 147334806710. Its totient is φ = 68000680008.

The previous prime is 102001020001. The next prime is 102001020029. The reversal of 102001020021 is 120020100201.

It can be written as a sum of positive squares in only one way, i.e., 79545997521 + 22455022500 = 282039^2 + 149850^2 .

It is not a de Polignac number, because 102001020021 - 2¹¹ = 102001017973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9), and also a Moran number because the ratio is a prime number: 11333446669 = 102001020021 / (1 + 0 + 2 + 0 + 0 + 1 + 0 + 2 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 102001019985 and 102001020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102001020029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 5666723326 + ... + 5666723343.

Almost surely, 2^102001020021 is an apocalyptic number.

It is an amenable number.

102001020021 is a deficient number, since it is larger than the sum of its proper divisors (45333786689).

102001020021 is a wasteful number, since it uses less digits than its factorization.

102001020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11333446675 (or 11333446672 counting only the distinct ones).

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

Adding to 102001020021 its reverse (120020100201), we get a palindrome (222021120222).

The spelling of 102001020021 in words is "one hundred two billion, one million, twenty thousand, twenty-one".