21205912 has 32 divisors (see below), whose sum is σ = 48938400. Its totient is φ = 8388864.

The previous prime is 21205909. The next prime is 21205913. The reversal of 21205912 is 21950212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205913) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13837 + ... + 15292.

It is an arithmetic number, because the mean of its divisors is an integer number (1529325).

Almost surely, 2^21205912 is an apocalyptic number.

It is an amenable number.

21205912 is an abundant number, since it is smaller than the sum of its proper divisors (27732488).

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

21205912 is a wasteful number, since it uses less digits than its factorization.

21205912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29155 (or 29151 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21205912 is about 4604.9877307111. The cubic root of 21205912 is about 276.7912253447.

The spelling of 21205912 in words is "twenty-one million, two hundred five thousand, nine hundred twelve".