26138991 has 4 divisors (see below), whose sum is σ = 34851992. Its totient is φ = 17425992.

The previous prime is 26138951. The next prime is 26138993. The reversal of 26138991 is 19983162.

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

It is not a de Polignac number, because 26138991 - 2¹⁰ = 26137967 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 (26138993) 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, 4356496 + ... + 4356501.

It is an arithmetic number, because the mean of its divisors is an integer number (8712998).

Almost surely, 2^26138991 is an apocalyptic number.

26138991 is a deficient number, since it is larger than the sum of its proper divisors (8713001).

26138991 is an equidigital number, since it uses as much as digits as its factorization.

26138991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8713000.

The product of its digits is 23328, while the sum is 39.

The square root of 26138991 is about 5112.6305362308. The cubic root of 26138991 is about 296.7765667535.

The spelling of 26138991 in words is "twenty-six million, one hundred thirty-eight thousand, nine hundred ninety-one".