25781663 has 4 divisors (see below), whose sum is σ = 25798080. Its totient is φ = 25765248.

The previous prime is 25781659. The next prime is 25781687. The reversal of 25781663 is 36618752.

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 25781663 - 2² = 25781659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25781603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5570 + ... + 9087.

It is an arithmetic number, because the mean of its divisors is an integer number (6449520).

Almost surely, 2^25781663 is an apocalyptic number.

25781663 is a deficient number, since it is larger than the sum of its proper divisors (16417).

25781663 is a wasteful number, since it uses less digits than its factorization.

25781663 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16416.

The product of its digits is 60480, while the sum is 38.

The square root of 25781663 is about 5077.5646721632. The cubic root of 25781663 is about 295.4180150725.

The spelling of 25781663 in words is "twenty-five million, seven hundred eighty-one thousand, six hundred sixty-three".