21518016 has 112 divisors (see below), whose sum is σ = 63239904. Its totient is φ = 6414336.

The previous prime is 21518009. The next prime is 21518027. The reversal of 21518016 is 61081512.

It is a Harshad number since it is a multiple of its sum of digits (24).

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, 92236 + ... + 92468.

It is an arithmetic number, because the mean of its divisors is an integer number (564642).

Almost surely, 2^21518016 is an apocalyptic number.

21518016 is a gapful number since it is divisible by the number (26) 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 21518016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31619952).

21518016 is an abundant number, since it is smaller than the sum of its proper divisors (41721888).

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

21518016 is a wasteful number, since it uses less digits than its factorization.

21518016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298 (or 288 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 24.

The square root of 21518016 is about 4638.7515561841. The cubic root of 21518016 is about 278.1425351230.

Adding to 21518016 its reverse (61081512), we get a palindrome (82599528).

The spelling of 21518016 in words is "twenty-one million, five hundred eighteen thousand, sixteen".