26257991 has 4 divisors (see below), whose sum is σ = 26499000. Its totient is φ = 26016984.

The previous prime is 26257967. The next prime is 26258039. The reversal of 26257991 is 19975262.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-26257991 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 (26257921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 120341 + ... + 120558.

It is an arithmetic number, because the mean of its divisors is an integer number (6624750).

Almost surely, 2^26257991 is an apocalyptic number.

26257991 is a deficient number, since it is larger than the sum of its proper divisors (241009).

26257991 is a wasteful number, since it uses less digits than its factorization.

26257991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241008.

The product of its digits is 68040, while the sum is 41.

The square root of 26257991 is about 5124.2551653875. The cubic root of 26257991 is about 297.2262519628.

The spelling of 26257991 in words is "twenty-six million, two hundred fifty-seven thousand, nine hundred ninety-one".