221387 has 4 divisors (see below), whose sum is σ = 222480. Its totient is φ = 220296.

The previous prime is 221327. The next prime is 221393. The reversal of 221387 is 783122.

221387 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 221387 - 2¹⁶ = 155851 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 221387.

It is not an unprimeable number, because it can be changed into a prime (221317) 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, 143 + ... + 680.

It is an arithmetic number, because the mean of its divisors is an integer number (55620).

2²²¹³⁸⁷ is an apocalyptic number.

221387 is a deficient number, since it is larger than the sum of its proper divisors (1093).

221387 is an equidigital number, since it uses as much as digits as its factorization.

221387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1092.

The product of its digits is 672, while the sum is 23.

The square root of 221387 is about 470.5177998758. The cubic root of 221387 is about 60.4947061825.

The spelling of 221387 in words is "two hundred twenty-one thousand, three hundred eighty-seven".