21357855 has 12 divisors (see below), whose sum is σ = 37020360. Its totient is φ = 11390832.

The previous prime is 21357827. The next prime is 21357857. The reversal of 21357855 is 55875312.

It is not a de Polignac number, because 21357855 - 2¹³ = 21349663 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21357857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 237265 + ... + 237354.

It is an arithmetic number, because the mean of its divisors is an integer number (3085030).

Almost surely, 2^21357855 is an apocalyptic number.

21357855 is a deficient number, since it is larger than the sum of its proper divisors (15662505).

21357855 is a wasteful number, since it uses less digits than its factorization.

21357855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474630 (or 474627 counting only the distinct ones).

The product of its digits is 42000, while the sum is 36.

The square root of 21357855 is about 4621.4559394200. The cubic root of 21357855 is about 277.4507338886.

The spelling of 21357855 in words is "twenty-one million, three hundred fifty-seven thousand, eight hundred fifty-five".