221869 has 4 divisors (see below), whose sum is σ = 223744. Its totient is φ = 219996.

The previous prime is 221849. The next prime is 221873. The reversal of 221869 is 968122.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 968122 = 2 ⋅484061.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221869 is a prime.

It is a super-2 number, since 2×221869² = 98451706322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221849) 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, 747 + ... + 1000.

It is an arithmetic number, because the mean of its divisors is an integer number (55936).

2²²¹⁸⁶⁹ is an apocalyptic number.

It is an amenable number.

221869 is a deficient number, since it is larger than the sum of its proper divisors (1875).

221869 is a wasteful number, since it uses less digits than its factorization.

221869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1874.

The product of its digits is 1728, while the sum is 28.

The square root of 221869 is about 471.0297230537. The cubic root of 221869 is about 60.5385770404.

Subtracting from 221869 its sum of digits (28), we obtain a square (221841 = 471²).

It can be divided in two parts, 22 and 1869, that added together give a triangular number (1891 = T₆₁).

The spelling of 221869 in words is "two hundred twenty-one thousand, eight hundred sixty-nine".