21630025 has 6 divisors (see below), whose sum is σ = 26821262. Its totient is φ = 17304000.

The previous prime is 21630019. The next prime is 21630031. The reversal of 21630025 is 52003612.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21630019) and next prime (21630031).

It can be written as a sum of positive squares in 3 ways, for example, as 1054729 + 20575296 = 1027^2 + 4536^2 .

It is not a de Polignac number, because 21630025 - 2⁹ = 21629513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21629984 and 21630011.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 432576 + ... + 432625.

Almost surely, 2^21630025 is an apocalyptic number.

21630025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21630025 is a deficient number, since it is larger than the sum of its proper divisors (5191237).

21630025 is an equidigital number, since it uses as much as digits as its factorization.

21630025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 865211 (or 865206 counting only the distinct ones).

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21630025 is about 4650.8090693986. The cubic root of 21630025 is about 278.6243107395.

Adding to 21630025 its reverse (52003612), we get a palindrome (73633637).

The spelling of 21630025 in words is "twenty-one million, six hundred thirty thousand, twenty-five".