221971 has 4 divisors (see below), whose sum is σ = 225352. Its totient is φ = 218592.

The previous prime is 221957. The next prime is 221987. The reversal of 221971 is 179122.

221971 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 an emirpimes, since its reverse is a distinct semiprime: 179122 = 2 ⋅89561.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221971 is a prime.

It is a super-2 number, since 2×221971² = 98542249682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221941) 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, 1590 + ... + 1723.

It is an arithmetic number, because the mean of its divisors is an integer number (56338).

2²²¹⁹⁷¹ is an apocalyptic number.

221971 is a deficient number, since it is larger than the sum of its proper divisors (3381).

221971 is an equidigital number, since it uses as much as digits as its factorization.

221971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3380.

The product of its digits is 252, while the sum is 22.

The square root of 221971 is about 471.1379840344. The cubic root of 221971 is about 60.5478527674.

Subtracting from 221971 its reverse (179122), we obtain a square (42849 = 207²).

The spelling of 221971 in words is "two hundred twenty-one thousand, nine hundred seventy-one".