25721855 has 4 divisors (see below), whose sum is σ = 30866232. Its totient is φ = 20577480.

The previous prime is 25721849. The next prime is 25721923. The reversal of 25721855 is 55812752.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 25721855 - 2⁶ = 25721791 is a prime.

It is a super-2 number, since 2×25721855² = 1323227649282050, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2572181 + ... + 2572190.

It is an arithmetic number, because the mean of its divisors is an integer number (7716558).

Almost surely, 2^25721855 is an apocalyptic number.

25721855 is a deficient number, since it is larger than the sum of its proper divisors (5144377).

25721855 is an equidigital number, since it uses as much as digits as its factorization.

25721855 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5144376.

The product of its digits is 28000, while the sum is 35.

The square root of 25721855 is about 5071.6718150921. The cubic root of 25721855 is about 295.1894024527.

The spelling of 25721855 in words is "twenty-five million, seven hundred twenty-one thousand, eight hundred fifty-five".