21228560 has 40 divisors (see below), whose sum is σ = 49550400. Its totient is φ = 8458112.

The previous prime is 21228553. The next prime is 21228569. The reversal of 21228560 is 6582212.

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 (21228569) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 35141 + ... + 35739.

It is an arithmetic number, because the mean of its divisors is an integer number (1238760).

Almost surely, 2^21228560 is an apocalyptic number.

21228560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21228560 is an abundant number, since it is smaller than the sum of its proper divisors (28321840).

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

21228560 is a wasteful number, since it uses less digits than its factorization.

21228560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1055 (or 1049 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 26.

The square root of 21228560 is about 4607.4461472707. The cubic root of 21228560 is about 276.8897283362.

The spelling of 21228560 in words is "twenty-one million, two hundred twenty-eight thousand, five hundred sixty".