25665949 has 2 divisors, whose sum is σ = 25665950. Its totient is φ = 25665948.

The previous prime is 25665947. The next prime is 25665961. The reversal of 25665949 is 94956652.

25665949 = T₄₁₃₅ + T₄₁₃₆ + T₄₁₃₇.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18429849 + 7236100 = 4293^2 + 2690^2 .

It is a cyclic number.

It is not a de Polignac number, because 25665949 - 2¹ = 25665947 is a prime.

Together with 25665947, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 25665899 and 25665908.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25665943) 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 as a sum of consecutive naturals, namely, 12832974 + 12832975.

It is an arithmetic number, because the mean of its divisors is an integer number (12832975).

Almost surely, 2^25665949 is an apocalyptic number.

25665949 is the 4137-th centered triangular number.

It is an amenable number.

25665949 is a deficient number, since it is larger than the sum of its proper divisors (1).

25665949 is an equidigital number, since it uses as much as digits as its factorization.

25665949 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 583200, while the sum is 46.

The square root of 25665949 is about 5066.1572221951. The cubic root of 25665949 is about 294.9753843293.

It can be divided in two parts, 2566 and 5949, that added together give a triangular number (8515 = T₁₃₀).

The spelling of 25665949 in words is "twenty-five million, six hundred sixty-five thousand, nine hundred forty-nine".