221947 has 4 divisors (see below), whose sum is σ = 242136. Its totient is φ = 201760.

The previous prime is 221941. The next prime is 221951. The reversal of 221947 is 749122.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221947 is a prime.

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, 10078 + ... + 10099.

It is an arithmetic number, because the mean of its divisors is an integer number (60534).

2²²¹⁹⁴⁷ is an apocalyptic number.

221947 is a deficient number, since it is larger than the sum of its proper divisors (20189).

221947 is a wasteful number, since it uses less digits than its factorization.

221947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20188.

The product of its digits is 1008, while the sum is 25.

The square root of 221947 is about 471.1125131006. The cubic root of 221947 is about 60.5456704991.

It can be divided in two parts, 22194 and 7, that added together give a square (22201 = 149²).

The spelling of 221947 in words is "two hundred twenty-one thousand, nine hundred forty-seven".