21516120 has 96 divisors (see below), whose sum is σ = 71182800. Its totient is φ = 5634816.

The previous prime is 21516119. The next prime is 21516127. The reversal of 21516120 is 2161512.

21516120 is a `hidden beast` number, since 2 + 1 + 51 + 612 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 21516093 and 21516102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21516127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20734 + ... + 21746.

Almost surely, 2^21516120 is an apocalyptic number.

21516120 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 21516120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35591400).

21516120 is an abundant number, since it is smaller than the sum of its proper divisors (49666680).

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

21516120 is a wasteful number, since it uses less digits than its factorization.

21516120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1089 (or 1082 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21516120 is about 4638.5471863505. The cubic root of 21516120 is about 278.1343656317.

Adding to 21516120 its reverse (2161512), we get a palindrome (23677632).

The spelling of 21516120 in words is "twenty-one million, five hundred sixteen thousand, one hundred twenty".