21168025 has 6 divisors (see below), whose sum is σ = 26248382. Its totient is φ = 16934400.

The previous prime is 21168023. The next prime is 21168031. The reversal of 21168025 is 52086112.

It can be written as a sum of positive squares in 3 ways, for example, as 301401 + 20866624 = 549^2 + 4568^2 .

It is not a de Polignac number, because 21168025 - 2¹ = 21168023 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 846721 = 21168025 / (2 + 1 + 1 + 6 + 8 + 0 + 2 + 5).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21168023) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 423336 + ... + 423385.

Almost surely, 2^21168025 is an apocalyptic number.

21168025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21168025 is a deficient number, since it is larger than the sum of its proper divisors (5080357).

21168025 is an equidigital number, since it uses as much as digits as its factorization.

21168025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 846731 (or 846726 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 21168025 is about 4600.8721999204. The cubic root of 21168025 is about 276.6262864245.

The spelling of 21168025 in words is "twenty-one million, one hundred sixty-eight thousand, twenty-five".