21205230525 has 36 divisors (see below), whose sum is σ = 38193180480. Its totient is φ = 11246253600.

The previous prime is 21205230523. The next prime is 21205230547. The reversal of 21205230525 is 52503250212.

It is not a de Polignac number, because 21205230525 - 2¹ = 21205230523 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205230523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 222981 + ... + 303530.

It is an arithmetic number, because the mean of its divisors is an integer number (1060921680).

Almost surely, 2^21205230525 is an apocalyptic number.

21205230525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21205230525 is a deficient number, since it is larger than the sum of its proper divisors (16987949955).

21205230525 is a wasteful number, since it uses less digits than its factorization.

21205230525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526706 (or 526698 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 27.

Adding to 21205230525 its reverse (52503250212), we get a palindrome (73708480737).

The spelling of 21205230525 in words is "twenty-one billion, two hundred five million, two hundred thirty thousand, five hundred twenty-five".