21242855 has 16 divisors (see below), whose sum is σ = 26956800. Its totient is φ = 16025760.

The previous prime is 21242839. The next prime is 21242857. The reversal of 21242855 is 55824212.

It is not a de Polignac number, because 21242855 - 2⁴ = 21242839 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21242857) 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, 29186 + ... + 29904.

It is an arithmetic number, because the mean of its divisors is an integer number (1684800).

Almost surely, 2^21242855 is an apocalyptic number.

21242855 is a deficient number, since it is larger than the sum of its proper divisors (5713945).

21242855 is a wasteful number, since it uses less digits than its factorization.

21242855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1054.

The product of its digits is 6400, while the sum is 29.

The square root of 21242855 is about 4608.9971794307. The cubic root of 21242855 is about 276.9518655473.

The spelling of 21242855 in words is "twenty-one million, two hundred forty-two thousand, eight hundred fifty-five".