21105120 has 48 divisors (see below), whose sum is σ = 66482640. Its totient is φ = 5627904.

The previous prime is 21105107. The next prime is 21105121. The reversal of 21105120 is 2150112.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21105096 and 21105105.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21105121) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21505 + ... + 22464.

It is an arithmetic number, because the mean of its divisors is an integer number (1385055).

Almost surely, 2^21105120 is an apocalyptic number.

21105120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21105120 is an abundant number, since it is smaller than the sum of its proper divisors (45377520).

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

21105120 is a wasteful number, since it uses less digits than its factorization.

21105120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43987 (or 43979 counting only the distinct ones).

The product of its (nonzero) digits is 20, while the sum is 12.

The square root of 21105120 is about 4594.0309097785. The cubic root of 21105120 is about 276.3519978520.

Adding to 21105120 its reverse (2150112), we get a palindrome (23255232).

The spelling of 21105120 in words is "twenty-one million, one hundred five thousand, one hundred twenty".