21011100120 has 48 divisors (see below), whose sum is σ = 68286076560. Its totient is φ = 5602959936.

The previous prime is 21011100079. The next prime is 21011100211. The reversal of 21011100120 is 2100111012.

It is a happy number.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29181724 + ... + 29182443.

It is an arithmetic number, because the mean of its divisors is an integer number (1422626595).

Almost surely, 2^21011100120 is an apocalyptic number.

21011100120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21011100120 is an abundant number, since it is smaller than the sum of its proper divisors (47274976440).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21011100120 is a wasteful number, since it uses less digits than its factorization.

21011100120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58364184 (or 58364177 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 9.

Adding to 21011100120 its reverse (2100111012), we get a palindrome (23111211132).

The spelling of 21011100120 in words is "twenty-one billion, eleven million, one hundred thousand, one hundred twenty".