221731730 has 32 divisors (see below), whose sum is σ = 454336128. Its totient is φ = 77123200.

The previous prime is 221731723. The next prime is 221731751. The reversal of 221731730 is 37137122.

It is a self number, because there is not a number n which added to its sum of digits gives 221731730.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 41291 + ... + 46350.

It is an arithmetic number, because the mean of its divisors is an integer number (14198004).

Almost surely, 2^221731730 is an apocalyptic number.

221731730 is an abundant number, since it is smaller than the sum of its proper divisors (232604398).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

221731730 is a wasteful number, since it uses less digits than its factorization.

221731730 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87682.

The product of its (nonzero) digits is 1764, while the sum is 26.

The square root of 221731730 is about 14890.6591526366. The cubic root of 221731730 is about 605.2608942402.

Adding to 221731730 its reverse (37137122), we get a palindrome (258868852).

The spelling of 221731730 in words is "two hundred twenty-one million, seven hundred thirty-one thousand, seven hundred thirty".