• 75 can be written using four 4's:

• 75^{2} = 5625 is the smallest square that contains exactly two digits '5'.

75 has 6 divisors (see below), whose sum is σ = 124. Its totient is φ = 40.

The previous prime is 73. The next prime is 79. The reversal of 75 is 57.

75 is nontrivially palindromic in base 14.

75 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a trimorphic number since its cube, 421875, ends in 75.

Together with 48 it forms a betrothed pair.

It is not a de Polignac number, because 75 - 2^{1} = 73 is a prime.

75 is a repfigit number.

It is a fibodiv number, since the Fibonacci-like sequence with seeds 7 and 5 contains 75 itself.

It is a Duffinian number.

75 is strictly pandigital in base 4.

75 is a lucky number.

75 is a nontrivial repdigit in base 14.

It is a plaindrome in base 7, base 8, base 11, base 13, base 14 and base 16.

It is a nialpdrome in base 3, base 5, base 9, base 10, base 12, base 14 and base 15.

It is a zygodrome in base 14.

It is a self number, because there is not a number *n* which added to its sum of digits gives 75.

It is an inconsummate number, since it does not exist a number *n* which divided by its sum of digits gives 75.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13 + ... + 17.

75 is the 5-th nonagonal number.

75 is a deficient number, since it is larger than the sum of its proper divisors (49).

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

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

The sum of its prime factors is 13 (or 8 counting only the distinct ones).

The product of its digits is 35, while the sum is 12.

The square root of 75 is about 8.6602540378. The cubic root of 75 is about 4.2171633265.

Multiplying 75 by its sum of digits (12), we get a square (900 = 30^{2}).

The spelling of 75 in words is "seventy-five", and thus it is an aban number, an oban number, and an uban number.

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