21251025 has 48 divisors (see below), whose sum is σ = 41118400. Its totient is φ = 10730880.

The previous prime is 21251023. The next prime is 21251053. The reversal of 21251025 is 52015212.

It is not a de Polignac number, because 21251025 - 2¹ = 21251023 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21250989 and 21251007.

It is not an unprimeable number, because it can be changed into a prime (21251023) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11997 + ... + 13653.

Almost surely, 2^21251025 is an apocalyptic number.

21251025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21251025 is a deficient number, since it is larger than the sum of its proper divisors (19867375).

21251025 is a wasteful number, since it uses less digits than its factorization.

21251025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1695 (or 1684 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21251025 is about 4609.8834041654. The cubic root of 21251025 is about 276.9873662169.

Adding to 21251025 its reverse (52015212), we get a palindrome (73266237).

The spelling of 21251025 in words is "twenty-one million, two hundred fifty-one thousand, twenty-five".