25516665 has 24 divisors (see below), whose sum is σ = 45756360. Its totient is φ = 13138944.

The previous prime is 25516663. The next prime is 25516693. The reversal of 25516665 is 56661552.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6411024 + 19105641 = 2532^2 + 4371^2 .

It is not a de Polignac number, because 25516665 - 2¹ = 25516663 is a prime.

It is a super-2 number, since 2×25516665² = 1302200385444450, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (25516663) 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 23 ways as a sum of consecutive naturals, for example, 8472 + ... + 11081.

It is an arithmetic number, because the mean of its divisors is an integer number (1906515).

Almost surely, 2^25516665 is an apocalyptic number.

It is an amenable number.

25516665 is a deficient number, since it is larger than the sum of its proper divisors (20239695).

25516665 is a wasteful number, since it uses less digits than its factorization.

25516665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19593 (or 19590 counting only the distinct ones).

The product of its digits is 54000, while the sum is 36.

The square root of 25516665 is about 5051.4022805554. The cubic root of 25516665 is about 294.4023714525.

It can be divided in two parts, 2551 and 6665, that added together give a square (9216 = 96²).

The spelling of 25516665 in words is "twenty-five million, five hundred sixteen thousand, six hundred sixty-five".