21545568 has 96 divisors (see below), whose sum is σ = 68584320. Its totient is φ = 6526080.

The previous prime is 21545551. The next prime is 21545603. The reversal of 21545568 is 86554512.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8371 + ... + 10637.

It is an arithmetic number, because the mean of its divisors is an integer number (714420).

Almost surely, 2^21545568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21545568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34292160).

21545568 is an abundant number, since it is smaller than the sum of its proper divisors (47038752).

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

21545568 is a wasteful number, since it uses less digits than its factorization.

21545568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2297 (or 2283 counting only the distinct ones).

The product of its digits is 48000, while the sum is 36.

The square root of 21545568 is about 4641.7203707246. The cubic root of 21545568 is about 278.2611971577.

The spelling of 21545568 in words is "twenty-one million, five hundred forty-five thousand, five hundred sixty-eight".