21205053 has 12 divisors (see below), whose sum is σ = 30719520. Its totient is φ = 14095176.

The previous prime is 21205049. The next prime is 21205099. The reversal of 21205053 is 35050212.

It is a happy number.

It is not a de Polignac number, because 21205053 - 2² = 21205049 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205043) 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 11 ways as a sum of consecutive naturals, for example, 51 + ... + 6512.

It is an arithmetic number, because the mean of its divisors is an integer number (2559960).

Almost surely, 2^21205053 is an apocalyptic number.

It is an amenable number.

21205053 is a deficient number, since it is larger than the sum of its proper divisors (9514467).

21205053 is a wasteful number, since it uses less digits than its factorization.

21205053 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6928 (or 6925 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 21205053 is about 4604.8944613313. The cubic root of 21205053 is about 276.7874879141.

Adding to 21205053 its reverse (35050212), we get a palindrome (56255265).

The spelling of 21205053 in words is "twenty-one million, two hundred five thousand, fifty-three".