25861981 has 4 divisors (see below), whose sum is σ = 27383292. Its totient is φ = 24340672.

The previous prime is 25861949. The next prime is 25861991. The reversal of 25861981 is 18916852.

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 9821956 + 16040025 = 3134^2 + 4005^2 .

It is a cyclic number.

It is not a de Polignac number, because 25861981 - 2⁵ = 25861949 is a prime.

It is a super-2 number, since 2×25861981² = 1337684122488722, 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 (25861931) 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, 760630 + ... + 760663.

It is an arithmetic number, because the mean of its divisors is an integer number (6845823).

Almost surely, 2^25861981 is an apocalyptic number.

It is an amenable number.

25861981 is a deficient number, since it is larger than the sum of its proper divisors (1521311).

25861981 is a wasteful number, since it uses less digits than its factorization.

25861981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1521310.

The product of its digits is 34560, while the sum is 40.

The square root of 25861981 is about 5085.4676284487. The cubic root of 25861981 is about 295.7244704431.

The spelling of 25861981 in words is "twenty-five million, eight hundred sixty-one thousand, nine hundred eighty-one".