21100100120 has 64 divisors (see below), whose sum is σ = 54837712800. Its totient is φ = 7221422080.

The previous prime is 21100100093. The next prime is 21100100143. The reversal of 21100100120 is 2100100112.

It is a Harshad number since it is a multiple of its sum of digits (8).

It is a junction number, because it is equal to n+sod(n) for n = 21100100098 and 21100100107.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1402955 + ... + 1417914.

Almost surely, 2^21100100120 is an apocalyptic number.

21100100120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21100100120 is an abundant number, since it is smaller than the sum of its proper divisors (33737612680).

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

21100100120 is a wasteful number, since it uses less digits than its factorization.

21100100120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2820908 (or 2820904 counting only the distinct ones).

The product of its (nonzero) digits is 4, while the sum is 8.

Adding to 21100100120 its reverse (2100100112), we get a palindrome (23200200232).

The spelling of 21100100120 in words is "twenty-one billion, one hundred million, one hundred thousand, one hundred twenty".