• 262 = 676 is the smallest square that contains exactly two digits '6'.
26 has 4
divisors (see below), whose sum is σ = 42
Its totient is φ = 12
The previous prime is 23. The next prime is 29. The reversal of 26 is 62.
Adding to 26 its reverse (62), we get a palindrome (88).
Subtracting 26 from its reverse (62), we obtain a triangular number (36 = T8).
26 is nontrivially palindromic in base 3, base 5 and base 12.
It is a Cunningham number, because it is equal to 52+1.
26 is an esthetic number in base 5 and base 8, because in such bases its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 62 = 2 ⋅31.
It is an interprime number because it is at equal distance from previous prime (23) and next prime (29).
It can be written as a sum of positive squares in only one way, i.e., 25 + 1 = 5^2 + 1^2
It is an Ulam number.
It is a cake number, because a cake can be divided into 26 parts by 5 planar cuts.
26 is an undulating number in base 5.
26 is a modest number, since divided by 6 gives 2 as remainder.
It is a Curzon number.
26 is a nontrivial repdigit in base 3 and base 12.
It is a plaindrome in base 3, base 4, base 7, base 9, base 10, base 11, base 12, base 14, base 15 and base 16.
It is a nialpdrome in base 3, base 6, base 8, base 12 and base 13.
It is a zygodrome in base 3 and base 12.
It is a pernicious number, because its binary representation contains a prime number (3) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5 + ... + 8.
It is equal to the Eulerian number A(5, 1).
26 is a deficient number, since it is larger than the sum of its proper divisors (16).
26 is a wasteful number, since it uses less digits than its factorization.
26 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 15.
The product of its digits is 12, while the sum is 8.
The square root of 26 is about 5.0990195136.
The cubic root of 26 is about 2.9624960684.
The spelling of 26 in words is "twenty-six", and thus it is an aban number, an oban number, and an uban number.