25218643 has 4 divisors (see below), whose sum is σ = 26545960. Its totient is φ = 23891328.

The previous prime is 25218607. The next prime is 25218647. The reversal of 25218643 is 34681252.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 25218643 - 2¹⁷ = 25087571 is a prime.

It is a super-2 number, since 2×25218643² = 1271959909522898, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25218647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 663630 + ... + 663667.

It is an arithmetic number, because the mean of its divisors is an integer number (6636490).

Almost surely, 2^25218643 is an apocalyptic number.

25218643 is a deficient number, since it is larger than the sum of its proper divisors (1327317).

25218643 is a wasteful number, since it uses less digits than its factorization.

25218643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1327316.

The product of its digits is 11520, while the sum is 31.

The square root of 25218643 is about 5021.8167031464. The cubic root of 25218643 is about 293.2517221597.

Adding to 25218643 its reverse (34681252), we get a palindrome (59899895).

The spelling of 25218643 in words is "twenty-five million, two hundred eighteen thousand, six hundred forty-three".