20012100021 has 12 divisors (see below), whose sum is σ = 28907598720. Its totient is φ = 13340831400.

The previous prime is 20012100019. The next prime is 20012100079. The reversal of 20012100021 is 12000121002.

It is not a de Polignac number, because 20012100021 - 2¹ = 20012100019 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 = 20012099976 and 20012100012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20012100011) 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, 358446 + ... + 410496.

It is an arithmetic number, because the mean of its divisors is an integer number (2408966560).

Almost surely, 2^20012100021 is an apocalyptic number.

It is an amenable number.

20012100021 is a deficient number, since it is larger than the sum of its proper divisors (8895498699).

20012100021 is a wasteful number, since it uses less digits than its factorization.

20012100021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94776 (or 94773 counting only the distinct ones).

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

Adding to 20012100021 its reverse (12000121002), we get a palindrome (32012221023).

The spelling of 20012100021 in words is "twenty billion, twelve million, one hundred thousand, twenty-one".