21675440 has 40 divisors (see below), whose sum is σ = 51575568. Its totient is φ = 8467200.

The previous prime is 21675427. The next prime is 21675449. The reversal of 21675440 is 4457612.

It is a tau number, because it is divible by the number of its divisors (40).

It is not an unprimeable number, because it can be changed into a prime (21675449) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 290 + ... + 6590.

Almost surely, 2^21675440 is an apocalyptic number.

21675440 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 21675440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25787784).

21675440 is an abundant number, since it is smaller than the sum of its proper divisors (29900128).

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

21675440 is a wasteful number, since it uses less digits than its factorization.

21675440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6357 (or 6351 counting only the distinct ones).

The product of its (nonzero) digits is 6720, while the sum is 29.

The square root of 21675440 is about 4655.6889930493. The cubic root of 21675440 is about 278.8191768627.

The spelling of 21675440 in words is "twenty-one million, six hundred seventy-five thousand, four hundred forty".