21550120 has 32 divisors (see below), whose sum is σ = 49079520. Its totient is φ = 8514880.

The previous prime is 21550099. The next prime is 21550127. The reversal of 21550120 is 2105512.

It is a junction number, because it is equal to n+sod(n) for n = 21550094 and 21550103.

It is not an unprimeable number, because it can be changed into a prime (21550127) 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, 75 + ... + 6565.

It is an arithmetic number, because the mean of its divisors is an integer number (1533735).

Almost surely, 2^21550120 is an apocalyptic number.

21550120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21550120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24539760).

21550120 is an abundant number, since it is smaller than the sum of its proper divisors (27529400).

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

21550120 is a wasteful number, since it uses less digits than its factorization.

21550120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6585 (or 6581 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21550120 is about 4642.2106802686. The cubic root of 21550120 is about 278.2807921509.

Adding to 21550120 its reverse (2105512), we get a palindrome (23655632).

The spelling of 21550120 in words is "twenty-one million, five hundred fifty thousand, one hundred twenty".