25947666565 has 8 divisors (see below), whose sum is σ = 31140908568. Its totient is φ = 20755660800.

The previous prime is 25947666443. The next prime is 25947666617. The reversal of 25947666565 is 56566674952.

It can be written as a sum of positive squares in 4 ways, for example, as 10938231396 + 15009435169 = 104586^2 + 122513^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 25947666565 - 2²⁹ = 25410795653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 262236 + ... + 347365.

It is an arithmetic number, because the mean of its divisors is an integer number (3892613571).

Almost surely, 2^25947666565 is an apocalyptic number.

It is an amenable number.

25947666565 is a deficient number, since it is larger than the sum of its proper divisors (5193242003).

25947666565 is an equidigital number, since it uses as much as digits as its factorization.

25947666565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 618119.

The product of its digits is 81648000, while the sum is 61.

It can be divided in two parts, 259476 and 66565, that added together give a square (326041 = 571²).

The spelling of 25947666565 in words is "twenty-five billion, nine hundred forty-seven million, six hundred sixty-six thousand, five hundred sixty-five".