21020120109 has 16 divisors (see below), whose sum is σ = 32779915200. Its totient is φ = 13275865008.

The previous prime is 21020120087. The next prime is 21020120111. The reversal of 21020120109 is 90102102012.

It is not a de Polignac number, because 21020120109 - 2⁹ = 21020119597 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21020120091 and 21020120100.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020120609) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20486934 + ... + 20487959.

It is an arithmetic number, because the mean of its divisors is an integer number (2048744700).

Almost surely, 2^21020120109 is an apocalyptic number.

It is an amenable number.

21020120109 is a deficient number, since it is larger than the sum of its proper divisors (11759795091).

21020120109 is a wasteful number, since it uses less digits than its factorization.

21020120109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40974921 (or 40974915 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The spelling of 21020120109 in words is "twenty-one billion, twenty million, one hundred twenty thousand, one hundred nine".