• 47 can be written using four 4's:

See also 113.

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47 has 2 divisors, whose sum is σ = 48. Its totient is φ = 46.

The previous prime is 43. The next prime is 53. The reversal of 47 is 74.

Added to its reverse (74) it gives a square (121 = 11²).

47 is an esthetic number in base 7, base 11 and base 15, because in such bases its adjacent digits differ by 1.

It is a weak prime.

47 is a truncatable prime.

It is a cyclic number.

It is not a de Polignac number, because 47 - 2² = 43 is a prime.

It is a Chen prime.

47 is a repfigit number.

It is a fibodiv number, since the Fibonacci-like sequence with seeds 4 and 7 contains 47 itself.

It is a Lucas number.

It is a magnanimous number.

It is an Ulam number.

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

It is a Carol number, being equal to (2³ - 1)² - 2.

It is a plaindrome in base 4, base 6, base 8, base 10, base 12, base 13, base 14 and base 16.

It is a nialpdrome in base 7, base 9, base 11 and base 15.

It is a congruent number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 23 + 24.

It is an arithmetic number, because the mean of its divisors is an integer number (24).

47 is a deficient number, since it is larger than the sum of its proper divisors (1).

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

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

The product of its digits is 28, while the sum is 11.

The square root of 47 is about 6.8556546004. The cubic root of 47 is about 3.6088260801.

Subtracting from 47 its sum of digits (11), we obtain a triangular number (36 = T₈).

Adding to 47 its reverse (74), we get a palindrome (121).

Subtracting 47 from its reverse (74), we obtain a cube (27 = 3³).

The spelling of 47 in words is "forty-seven", and thus it is an aban number, an iban number, and an uban number.