25381 has 4 divisors (see below), whose sum is σ = 26892. Its totient is φ = 23872.
The previous prime is 25373. The next prime is 25391. The reversal of 25381 is 18352.
It is a happy number.
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 21025 + 4356 = 145^2 + 66^2 .
It is a cyclic number.
It is not a de Polignac number, because 25381 - 23 = 25373 is a prime.
It is a super-2 number, since 2×253812 = 1288390322, which contains 22 as substring.
It is an Ulam number.
It is a Duffinian number.
It is a plaindrome in base 7.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (25301) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 730 + ... + 763.
It is an arithmetic number, because the mean of its divisors is an integer number (6723).
225381 is an apocalyptic number.
It is an amenable number.
25381 is a deficient number, since it is larger than the sum of its proper divisors (1511).
25381 is a wasteful number, since it uses less digits than its factorization.
25381 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 1510.
The product of its digits is 240, while the sum is 19.
The square root of 25381 is about 159.3141550522. The cubic root of 25381 is about 29.3879692241.
It can be divided in two parts, 25 and 381, that added together give a triangular number (406 = T28).
The spelling of 25381 in words is "twenty-five thousand, three hundred eighty-one".
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