21308525 has 12 divisors (see below), whose sum is σ = 30197472. Its totient is φ = 14611440.

The previous prime is 21308509. The next prime is 21308527. The reversal of 21308525 is 52580312.

It is not a de Polignac number, because 21308525 - 2⁴ = 21308509 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21308494 and 21308503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21308527) 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, 60707 + ... + 61056.

It is an arithmetic number, because the mean of its divisors is an integer number (2516456).

Almost surely, 2^21308525 is an apocalyptic number.

21308525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21308525 is a deficient number, since it is larger than the sum of its proper divisors (8888947).

21308525 is a wasteful number, since it uses less digits than its factorization.

21308525 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121780 (or 121775 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 26.

The square root of 21308525 is about 4616.1157914420. The cubic root of 21308525 is about 277.2369609302.

Adding to 21308525 its reverse (52580312), we get a palindrome (73888837).

The spelling of 21308525 in words is "twenty-one million, three hundred eight thousand, five hundred twenty-five".