21628560 has 80 divisors (see below), whose sum is σ = 67513536. Its totient is φ = 5727744.

The previous prime is 21628553. The next prime is 21628567. The reversal of 21628560 is 6582612.

It is an interprime number because it is at equal distance from previous prime (21628553) and next prime (21628567).

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21628567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 54282 + ... + 54678.

Almost surely, 2^21628560 is an apocalyptic number.

21628560 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 21628560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33756768).

21628560 is an abundant number, since it is smaller than the sum of its proper divisors (45884976).

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

21628560 is a wasteful number, since it uses less digits than its factorization.

21628560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 640 (or 634 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 21628560 is about 4650.6515672538. The cubic root of 21628560 is about 278.6180201961.

The spelling of 21628560 in words is "twenty-one million, six hundred twenty-eight thousand, five hundred sixty".