21840328 has 8 divisors (see below), whose sum is σ = 40950630. Its totient is φ = 10920160.

The previous prime is 21840319. The next prime is 21840361. The reversal of 21840328 is 82304812.

It can be written as a sum of positive squares in only one way, i.e., 15069924 + 6770404 = 3882^2 + 2602^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21840296 and 21840305.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1365013 + ... + 1365028.

Almost surely, 2^21840328 is an apocalyptic number.

It is an amenable number.

21840328 is a deficient number, since it is larger than the sum of its proper divisors (19110302).

21840328 is a wasteful number, since it uses less digits than its factorization.

21840328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2730047 (or 2730043 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 21840328 is about 4673.3636708478. The cubic root of 21840328 is about 279.5243966872.

The spelling of 21840328 in words is "twenty-one million, eight hundred forty thousand, three hundred twenty-eight".