21221065125 has 64 divisors (see below), whose sum is σ = 42253585920. Its totient is φ = 10447272000.

The previous prime is 21221065079. The next prime is 21221065163. The reversal of 21221065125 is 52156012212.

21221065125 is a `hidden beast` number, since 2 + 1 + 2 + 2 + 1 + 0 + 651 + 2 + 5 = 666.

It is not a de Polignac number, because 21221065125 - 2¹¹ = 21221063077 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 197961 + ... + 285710.

It is an arithmetic number, because the mean of its divisors is an integer number (660212280).

Almost surely, 2^21221065125 is an apocalyptic number.

21221065125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21221065125 is a deficient number, since it is larger than the sum of its proper divisors (21032520795).

21221065125 is a wasteful number, since it uses less digits than its factorization.

21221065125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 483708 (or 483692 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

Adding to 21221065125 its reverse (52156012212), we get a palindrome (73377077337).

The spelling of 21221065125 in words is "twenty-one billion, two hundred twenty-one million, sixty-five thousand, one hundred twenty-five".