21575680 has 144 divisors (see below), whose sum is σ = 61621560. Its totient is φ = 7225344.

The previous prime is 21575677. The next prime is 21575747. The reversal of 21575680 is 8657512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 501739 + ... + 501781.

Almost surely, 2^21575680 is an apocalyptic number.

21575680 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 21575680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30810780).

21575680 is an abundant number, since it is smaller than the sum of its proper divisors (40045880).

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

21575680 is an equidigital number, since it uses as much as digits as its factorization.

21575680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 21575680 is about 4644.9628631454. The cubic root of 21575680 is about 278.3907690602.

The spelling of 21575680 in words is "twenty-one million, five hundred seventy-five thousand, six hundred eighty".