221731649 has 4 divisors (see below), whose sum is σ = 227139780. Its totient is φ = 216323520.

The previous prime is 221731613. The next prime is 221731667. The reversal of 221731649 is 946137122.

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

It can be written as a sum of positive squares in 2 ways, for example, as 108160000 + 113571649 = 10400^2 + 10657^2 .

It is a cyclic number.

It is not a de Polignac number, because 221731649 - 2¹⁶ = 221666113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221731669) 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, 2704004 + ... + 2704085.

It is an arithmetic number, because the mean of its divisors is an integer number (56784945).

Almost surely, 2^221731649 is an apocalyptic number.

It is an amenable number.

221731649 is a deficient number, since it is larger than the sum of its proper divisors (5408131).

221731649 is an equidigital number, since it uses as much as digits as its factorization.

221731649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5408130.

The product of its digits is 18144, while the sum is 35.

The square root of 221731649 is about 14890.6564328105. The cubic root of 221731649 is about 605.2608205383.

The spelling of 221731649 in words is "two hundred twenty-one million, seven hundred thirty-one thousand, six hundred forty-nine".