21088518 has 64 divisors (see below), whose sum is σ = 49351680. Its totient is φ = 5940000.

The previous prime is 21088513. The next prime is 21088519. The reversal of 21088518 is 81588012.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21088513) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 83893 + ... + 84143.

It is an arithmetic number, because the mean of its divisors is an integer number (771120).

Almost surely, 2^21088518 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21088518, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24675840).

21088518 is an abundant number, since it is smaller than the sum of its proper divisors (28263162).

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

21088518 is a wasteful number, since it uses less digits than its factorization.

21088518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353.

The product of its (nonzero) digits is 5120, while the sum is 33.

The square root of 21088518 is about 4592.2236443797. The cubic root of 21088518 is about 276.2795162391.

The spelling of 21088518 in words is "twenty-one million, eighty-eight thousand, five hundred eighteen".