21165503025 has 24 divisors (see below), whose sum is σ = 35053318944. Its totient is φ = 11269014400.

The previous prime is 21165503011. The next prime is 21165503041. The reversal of 21165503025 is 52030556112.

It is a happy number.

It is not a de Polignac number, because 21165503025 - 2⁵ = 21165502993 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21165502983 and 21165503001.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 196356 + ... + 284405.

It is an arithmetic number, because the mean of its divisors is an integer number (1460554956).

Almost surely, 2^21165503025 is an apocalyptic number.

21165503025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21165503025 is a deficient number, since it is larger than the sum of its proper divisors (13887815919).

21165503025 is a wasteful number, since it uses less digits than its factorization.

21165503025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481361 (or 481356 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 21165503025 in words is "twenty-one billion, one hundred sixty-five million, five hundred three thousand, twenty-five".