21364518 has 64 divisors (see below), whose sum is σ = 51425280. Its totient is φ = 5788800.

The previous prime is 21364517. The next prime is 21364547. The reversal of 21364518 is 81546312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21364513) 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, 79288 + ... + 79556.

It is an arithmetic number, because the mean of its divisors is an integer number (803520).

Almost surely, 2^21364518 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21364518, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25712640).

21364518 is an abundant number, since it is smaller than the sum of its proper divisors (30060762).

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

21364518 is a wasteful number, since it uses less digits than its factorization.

21364518 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 373.

The product of its digits is 5760, while the sum is 30.

The square root of 21364518 is about 4622.1767599260. The cubic root of 21364518 is about 277.4795829472.

The spelling of 21364518 in words is "twenty-one million, three hundred sixty-four thousand, five hundred eighteen".