21545025 has 24 divisors (see below), whose sum is σ = 35979840. Its totient is φ = 11375040.

The previous prime is 21545011. The next prime is 21545039. The reversal of 21545025 is 52054512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21545011) and next prime (21545039).

It is not a de Polignac number, because 21545025 - 2⁴ = 21545009 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21544986 and 21545004.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6331 + ... + 9119.

It is an arithmetic number, because the mean of its divisors is an integer number (1499160).

Almost surely, 2^21545025 is an apocalyptic number.

21545025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21545025 is a deficient number, since it is larger than the sum of its proper divisors (14434815).

21545025 is a wasteful number, since it uses less digits than its factorization.

21545025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2905 (or 2900 counting only the distinct ones).

The product of its (nonzero) digits is 2000, while the sum is 24.

The square root of 21545025 is about 4641.6618791118. The cubic root of 21545025 is about 278.2588595215.

Adding to 21545025 its reverse (52054512), we get a palindrome (73599537).

The spelling of 21545025 in words is "twenty-one million, five hundred forty-five thousand, twenty-five".