Search a number
BaseRepresentation
bin10101101011
31220101
4111223
521022
610231
74021
oct2553
91811
101387
111051
12977
13829
14711
15627
hex56b

1387 has 4 divisors (see below), whose sum is σ = 1480. Its totient is φ = 1296.

The previous prime is 1381. The next prime is 1399. The reversal of 1387 is 7831.

It can be divided in two parts, 13 and 87, that added together give a square (100 = 102).

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 7831 = 41191.

It is a 4-Lehmer number, since φ(1387) divides (1387-1)4.

It is a cyclic number.

It is not a de Polignac number, because 1387 - 27 = 1259 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19), and also a Moran number because the ratio is a prime number: 73 = 1387 / (1 + 3 + 8 + 7).

It is an Ulam number.

It is a Duffinian number.

1387 is a lucky number.

It is a plaindrome in base 4 and base 16.

It is a nialpdrome in base 12 and base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18 + ... + 55.

It is an arithmetic number, because the mean of its divisors is an integer number (370).

It is a Poulet number, since it divides 21386-1.

1387 is the 19-th decagonal number.

1387 is the 22-nd hex number.

1387 is a deficient number, since it is larger than the sum of its proper divisors (93).

1387 is an equidigital number, since it uses as much as digits as its factorization.

1387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92.

The product of its digits is 168, while the sum is 19.

The square root of 1387 is about 37.2424488991. The cubic root of 1387 is about 11.1521556022.

The spelling of 1387 in words is "one thousand, three hundred eighty-seven".

Divisors: 1 19 73 1387