21055356 has 48 divisors (see below), whose sum is σ = 62388480. Its totient is φ = 6015600.

The previous prime is 21055351. The next prime is 21055379. The reversal of 21055356 is 65355012.

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 (21055351) 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, 13170 + ... + 14681.

It is an arithmetic number, because the mean of its divisors is an integer number (1299760).

Almost surely, 2^21055356 is an apocalyptic number.

It is an amenable number.

21055356 is an abundant number, since it is smaller than the sum of its proper divisors (41333124).

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

21055356 is a wasteful number, since it uses less digits than its factorization.

21055356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27871 (or 27863 counting only the distinct ones).

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

The square root of 21055356 is about 4588.6115547080. The cubic root of 21055356 is about 276.1346224163.

The spelling of 21055356 in words is "twenty-one million, fifty-five thousand, three hundred fifty-six".