21943040 has 144 divisors (see below), whose sum is σ = 62791680. Its totient is φ = 7188480.

The previous prime is 21943037. The next prime is 21943069. The reversal of 21943040 is 4034912.

It is a junction number, because it is equal to n+sod(n) for n = 21942997 and 21943015.

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, 277721 + ... + 277799.

Almost surely, 2^21943040 is an apocalyptic number.

21943040 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 21943040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31395840).

21943040 is an abundant number, since it is smaller than the sum of its proper divisors (40848640).

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

21943040 is an equidigital number, since it uses as much as digits as its factorization.

21943040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138 (or 124 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21943040 is about 4684.3398681138. The cubic root of 21943040 is about 279.9618995777.

Adding to 21943040 its reverse (4034912), we get a palindrome (25977952).

The spelling of 21943040 in words is "twenty-one million, nine hundred forty-three thousand, forty".