221731424 has 12 divisors (see below), whose sum is σ = 436533804. Its totient is φ = 110865696.

The previous prime is 221731423. The next prime is 221731439. The reversal of 221731424 is 424137122.

221731424 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a junction number, because it is equal to n+sod(n) for n = 221731393 and 221731402.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221731423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3464522 + ... + 3464585.

It is an arithmetic number, because the mean of its divisors is an integer number (36377817).

Almost surely, 2^221731424 is an apocalyptic number.

It is an amenable number.

221731424 is a deficient number, since it is larger than the sum of its proper divisors (214802380).

221731424 is an equidigital number, since it uses as much as digits as its factorization.

221731424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6929117 (or 6929109 counting only the distinct ones).

The product of its digits is 2688, while the sum is 26.

The square root of 221731424 is about 14890.6488777353. The cubic root of 221731424 is about 605.2606158108.

Adding to 221731424 its reverse (424137122), we get a palindrome (645868546).

The spelling of 221731424 in words is "two hundred twenty-one million, seven hundred thirty-one thousand, four hundred twenty-four".