21445025 has 48 divisors (see below), whose sum is σ = 32378880. Its totient is φ = 13780800.

The previous prime is 21445013. The next prime is 21445031. The reversal of 21445025 is 52054412.

It is a happy number.

It is not a de Polignac number, because 21445025 - 2⁶ = 21444961 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 320042 + ... + 320108.

It is an arithmetic number, because the mean of its divisors is an integer number (674560).

Almost surely, 2^21445025 is an apocalyptic number.

21445025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21445025 is a deficient number, since it is larger than the sum of its proper divisors (10933855).

21445025 is a wasteful number, since it uses less digits than its factorization.

21445025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 174 (or 169 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 23.

The square root of 21445025 is about 4630.8773466806. The cubic root of 21445025 is about 277.8276842183.

Adding to 21445025 its reverse (52054412), we get a palindrome (73499437).

The spelling of 21445025 in words is "twenty-one million, four hundred forty-five thousand, twenty-five".