21388560 has 40 divisors (see below), whose sum is σ = 66305280. Its totient is φ = 5703552.

The previous prime is 21388559. The next prime is 21388583. The reversal of 21388560 is 6588312.

It is a happy number.

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

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44320 + ... + 44799.

It is an arithmetic number, because the mean of its divisors is an integer number (1657632).

Almost surely, 2^21388560 is an apocalyptic number.

21388560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21388560 is an abundant number, since it is smaller than the sum of its proper divisors (44916720).

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

21388560 is a wasteful number, since it uses less digits than its factorization.

21388560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89135 (or 89129 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21388560 is about 4624.7767513687. The cubic root of 21388560 is about 277.5836287189.

The spelling of 21388560 in words is "twenty-one million, three hundred eighty-eight thousand, five hundred sixty".