287221 has 4 divisors (see below), whose sum is σ = 313344. Its totient is φ = 261100.

The previous prime is 287219. The next prime is 287233. The reversal of 287221 is 122782.

287221 = T₂₂₃ + T₂₂₄ + ... + T₂₃₃.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 287221 - 2¹ = 287219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 287192 and 287201.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (287251) 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, 13045 + ... + 13066.

It is an arithmetic number, because the mean of its divisors is an integer number (78336).

2²⁸⁷²²¹ is an apocalyptic number.

It is an amenable number.

287221 is a deficient number, since it is larger than the sum of its proper divisors (26123).

287221 is a wasteful number, since it uses less digits than its factorization.

287221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26122.

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

The square root of 287221 is about 535.9300327468. The cubic root of 287221 is about 65.9789495157.

The spelling of 287221 in words is "two hundred eighty-seven thousand, two hundred twenty-one".