• 745² = 555025 is the smallest square that contains exactly four digits '5'.

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745 has 4 divisors (see below), whose sum is σ = 900. Its totient is φ = 592.

The previous prime is 743. The next prime is 751. The reversal of 745 is 547.

745 is nontrivially palindromic in base 13 and base 14.

745 is an esthetic number in base 13, because in such base its adjacent digits differ by 1.

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

It can be written as a sum of positive squares in 2 ways, for example, as 169 + 576 = 13^2 + 24^2 .

It is a cyclic number.

It is not a de Polignac number, because 745 - 2¹ = 743 is a prime.

It is an alternating number because its digits alternate between odd and even.

745 is an undulating number in base 13 and base 14.

745 is a lucky number.

It is a plaindrome in base 15.

It is a nialpdrome in base 12.

It is not an unprimeable number, because it can be changed into a prime (743) 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, 70 + ... + 79.

It is an arithmetic number, because the mean of its divisors is an integer number (225).

It is an amenable number.

745 is a deficient number, since it is larger than the sum of its proper divisors (155).

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

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

The sum of its prime factors is 154.

The product of its digits is 140, while the sum is 16.

The square root of 745 is about 27.2946881279. The cubic root of 745 is about 9.0653677013.

Subtracting from 745 its sum of digits (16), we obtain a 6-th power (729 = 3⁶).

The spelling of 745 in words is "seven hundred forty-five", and thus it is an aban number.