21943680 has 128 divisors (see below), whose sum is σ = 76377600. Its totient is φ = 5314560.

The previous prime is 21943673. The next prime is 21943687. The reversal of 21943680 is 8634912.

It is an interprime number because it is at equal distance from previous prime (21943673) and next prime (21943687).

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

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 (21943687) 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 15 ways as a sum of consecutive naturals, for example, 20601 + ... + 21639.

It is an arithmetic number, because the mean of its divisors is an integer number (596700).

Almost surely, 2^21943680 is an apocalyptic number.

21943680 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 21943680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38188800).

21943680 is an abundant number, since it is smaller than the sum of its proper divisors (54433920).

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

21943680 is a wasteful number, since it uses less digits than its factorization.

21943680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1072 (or 1060 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 33.

The square root of 21943680 is about 4684.4081803361. The cubic root of 21943680 is about 279.9646213804.

The spelling of 21943680 in words is "twenty-one million, nine hundred forty-three thousand, six hundred eighty".