25561609 has 2 divisors, whose sum is σ = 25561610. Its totient is φ = 25561608.

The previous prime is 25561603. The next prime is 25561621. The reversal of 25561609 is 90616552.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22534009 + 3027600 = 4747^2 + 1740^2 .

It is a cyclic number.

It is not a de Polignac number, because 25561609 - 2¹³ = 25553417 is a prime.

It is not a weakly prime, because it can be changed into another prime (25561603) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12780804 + 12780805.

It is an arithmetic number, because the mean of its divisors is an integer number (12780805).

Almost surely, 2^25561609 is an apocalyptic number.

It is an amenable number.

25561609 is a deficient number, since it is larger than the sum of its proper divisors (1).

25561609 is an equidigital number, since it uses as much as digits as its factorization.

25561609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 16200, while the sum is 34.

The square root of 25561609 is about 5055.8489890423. The cubic root of 25561609 is about 294.5751194616.

The spelling of 25561609 in words is "twenty-five million, five hundred sixty-one thousand, six hundred nine".