21356608 has 112 divisors (see below), whose sum is σ = 55189120. Its totient is φ = 7962624.

The previous prime is 21356603. The next prime is 21356609. The reversal of 21356608 is 80665312.

It is a tau number, because it is divible by the number of its divisors (112).

It is a super-2 number, since 2×21356608² = 912209410531328, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21356608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356603) 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, 110560 + ... + 110752.

It is an arithmetic number, because the mean of its divisors is an integer number (492760).

Almost surely, 2^21356608 is an apocalyptic number.

21356608 is a gapful number since it is divisible by the number (28) 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 21356608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27594560).

21356608 is an abundant number, since it is smaller than the sum of its proper divisors (33832512).

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

21356608 is a wasteful number, since it uses less digits than its factorization.

21356608 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 244 (or 234 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 21356608 is about 4621.3210232573. The cubic root of 21356608 is about 277.4453340361.

The spelling of 21356608 in words is "twenty-one million, three hundred fifty-six thousand, six hundred eight".