25531991 has 4 divisors (see below), whose sum is σ = 26875800. Its totient is φ = 24188184.

The previous prime is 25531973. The next prime is 25531993. The reversal of 25531991 is 19913552.

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

It is a cyclic number.

It is not a de Polignac number, because 25531991 - 2⁶ = 25531927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25531993) 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, 671876 + ... + 671913.

It is an arithmetic number, because the mean of its divisors is an integer number (6718950).

Almost surely, 2^25531991 is an apocalyptic number.

25531991 is a deficient number, since it is larger than the sum of its proper divisors (1343809).

25531991 is a wasteful number, since it uses less digits than its factorization.

25531991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1343808.

The product of its digits is 12150, while the sum is 35.

The square root of 25531991 is about 5052.9190573371. The cubic root of 25531991 is about 294.4613016680.

The spelling of 25531991 in words is "twenty-five million, five hundred thirty-one thousand, nine hundred ninety-one".