25505981 has 4 divisors (see below), whose sum is σ = 25855452. Its totient is φ = 25156512.

The previous prime is 25505971. The next prime is 25505989. The reversal of 25505981 is 18950552.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14182756 + 11323225 = 3766^2 + 3365^2 .

It is a cyclic number.

It is not a de Polignac number, because 25505981 - 2⁶ = 25505917 is a prime.

It is a super-2 number, since 2×25505981² = 1301110133544722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25505989) 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, 174626 + ... + 174771.

It is an arithmetic number, because the mean of its divisors is an integer number (6463863).

Almost surely, 2^25505981 is an apocalyptic number.

It is an amenable number.

25505981 is a deficient number, since it is larger than the sum of its proper divisors (349471).

25505981 is an equidigital number, since it uses as much as digits as its factorization.

25505981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 349470.

The product of its (nonzero) digits is 18000, while the sum is 35.

The square root of 25505981 is about 5050.3446417052. The cubic root of 25505981 is about 294.3612762958.

The spelling of 25505981 in words is "twenty-five million, five hundred five thousand, nine hundred eighty-one".