20100120021 has 24 divisors (see below), whose sum is σ = 29495880960. Its totient is φ = 13187772000.

The previous prime is 20100120011. The next prime is 20100120031. The reversal of 20100120021 is 12002100102.

It is an interprime number because it is at equal distance from previous prime (20100120011) and next prime (20100120031).

It is not a de Polignac number, because 20100120021 - 2²⁷ = 19965902293 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 = 20100119985 and 20100120012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20100120011) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 175671 + ... + 266571.

It is an arithmetic number, because the mean of its divisors is an integer number (1228995040).

Almost surely, 2^20100120021 is an apocalyptic number.

It is an amenable number.

20100120021 is a deficient number, since it is larger than the sum of its proper divisors (9395760939).

20100120021 is a wasteful number, since it uses less digits than its factorization.

20100120021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91297 (or 91294 counting only the distinct ones).

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

Adding to 20100120021 its reverse (12002100102), we get a palindrome (32102220123).

The spelling of 20100120021 in words is "twenty billion, one hundred million, one hundred twenty thousand, twenty-one".