21356055 has 80 divisors (see below), whose sum is σ = 45348864. Its totient is φ = 9447840.

The previous prime is 21356051. The next prime is 21356089. The reversal of 21356055 is 55065312.

21356055 is a `hidden beast` number, since 21 + 35 + 605 + 5 = 666.

It is not a de Polignac number, because 21356055 - 2² = 21356051 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21356051) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 688890 + ... + 688920.

Almost surely, 2^21356055 is an apocalyptic number.

21356055 is an abundant number, since it is smaller than the sum of its proper divisors (23992809).

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

21356055 is an frugal number, since it uses more digits than its factorization.

21356055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 46 counting only the distinct ones).

The product of its (nonzero) digits is 4500, while the sum is 27.

The square root of 21356055 is about 4621.2611914931. The cubic root of 21356055 is about 277.4429393269.

The spelling of 21356055 in words is "twenty-one million, three hundred fifty-six thousand, fifty-five".