25216509 has 4 divisors (see below), whose sum is σ = 33622016. Its totient is φ = 16811004.

The previous prime is 25216507. The next prime is 25216567. The reversal of 25216509 is 90561252.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 25216509 - 2¹ = 25216507 is a prime.

It is a super-2 number, since 2×25216509² = 1271744652294162, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25216507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4202749 + ... + 4202754.

It is an arithmetic number, because the mean of its divisors is an integer number (8405504).

Almost surely, 2^25216509 is an apocalyptic number.

It is an amenable number.

25216509 is a deficient number, since it is larger than the sum of its proper divisors (8405507).

25216509 is an equidigital number, since it uses as much as digits as its factorization.

25216509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8405506.

The product of its (nonzero) digits is 5400, while the sum is 30.

The square root of 25216509 is about 5021.6042257430. The cubic root of 25216509 is about 293.2434502788.

It can be divided in two parts, 252 and 16509, that added together give a palindrome (16761).

The spelling of 25216509 in words is "twenty-five million, two hundred sixteen thousand, five hundred nine".