21800064 has 128 divisors (see below), whose sum is σ = 68201280. Its totient is φ = 6082560.

The previous prime is 21800059. The next prime is 21800081. The reversal of 21800064 is 46000812.

It is a tau number, because it is divible by the number of its divisors (128).

It is a self number, because there is not a number n which added to its sum of digits gives 21800064.

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, 54714 + ... + 55110.

Almost surely, 2^21800064 is an apocalyptic number.

21800064 is a gapful number since it is divisible by the number (24) 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 21800064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34100640).

21800064 is an abundant number, since it is smaller than the sum of its proper divisors (46401216).

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

21800064 is a wasteful number, since it uses less digits than its factorization.

21800064 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 438 (or 426 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21800064 is about 4669.0538656135. The cubic root of 21800064 is about 279.3525174967.

Adding to 21800064 its reverse (46000812), we get a palindrome (67800876).

The spelling of 21800064 in words is "twenty-one million, eight hundred thousand, sixty-four".