25311981 has 4 divisors (see below), whose sum is σ = 33749312. Its totient is φ = 16874652.

The previous prime is 25311967. The next prime is 25312019. The reversal of 25311981 is 18911352.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 25311981 - 2²³ = 16923373 is a prime.

It is a super-2 number, since 2×25311981² = 1281392764288722, 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 (25311931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4218661 + ... + 4218666.

It is an arithmetic number, because the mean of its divisors is an integer number (8437328).

Almost surely, 2^25311981 is an apocalyptic number.

It is an amenable number.

25311981 is a deficient number, since it is larger than the sum of its proper divisors (8437331).

25311981 is an equidigital number, since it uses as much as digits as its factorization.

25311981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8437330.

The product of its digits is 2160, while the sum is 30.

The square root of 25311981 is about 5031.1013704755. The cubic root of 25311981 is about 293.6130663418.

The spelling of 25311981 in words is "twenty-five million, three hundred eleven thousand, nine hundred eighty-one".