102100020021 has 16 divisors (see below), whose sum is σ = 153389704320. Its totient is φ = 67107993120.

The previous prime is 102100020017. The next prime is 102100020047. The reversal of 102100020021 is 120020001201.

It is not a de Polignac number, because 102100020021 - 2² = 102100020017 is a prime.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 102100019985 and 102100020012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (102100020721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26628240 + ... + 26632073.

It is an arithmetic number, because the mean of its divisors is an integer number (9586856520).

Almost surely, 2^102100020021 is an apocalyptic number.

It is an amenable number.

102100020021 is a deficient number, since it is larger than the sum of its proper divisors (51289684299).

102100020021 is an equidigital number, since it uses as much as digits as its factorization.

102100020021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53260393 (or 53260387 counting only the distinct ones).

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

Adding to 102100020021 its reverse (120020001201), we get a palindrome (222120021222).

The spelling of 102100020021 in words is "one hundred two billion, one hundred million, twenty thousand, twenty-one".