221287 has 4 divisors (see below), whose sum is σ = 241416. Its totient is φ = 201160.

The previous prime is 221281. The next prime is 221303. The reversal of 221287 is 782122.

221287 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.

It is a cyclic number.

It is not a de Polignac number, because 221287 - 2⁷ = 221159 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221281) 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, 10048 + ... + 10069.

It is an arithmetic number, because the mean of its divisors is an integer number (60354).

2²²¹²⁸⁷ is an apocalyptic number.

221287 is a deficient number, since it is larger than the sum of its proper divisors (20129).

221287 is a wasteful number, since it uses less digits than its factorization.

221287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20128.

The product of its digits is 448, while the sum is 22.

The square root of 221287 is about 470.4115219677. The cubic root of 221287 is about 60.4855963708.

The spelling of 221287 in words is "two hundred twenty-one thousand, two hundred eighty-seven".