217221730 has 16 divisors (see below), whose sum is σ = 426544704. Its totient is φ = 78989680.

The previous prime is 217221721. The next prime is 217221749. The reversal of 217221730 is 37122712.

It is a junction number, because it is equal to n+sod(n) for n = 217221695 and 217221704.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 987262 + ... + 987481.

It is an arithmetic number, because the mean of its divisors is an integer number (26659044).

Almost surely, 2^217221730 is an apocalyptic number.

217221730 is a deficient number, since it is larger than the sum of its proper divisors (209322974).

217221730 is a wasteful number, since it uses less digits than its factorization.

217221730 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1974761.

The product of its (nonzero) digits is 1176, while the sum is 25.

The square root of 217221730 is about 14738.4439477171. The cubic root of 217221730 is about 601.1291053505.

The spelling of 217221730 in words is "two hundred seventeen million, two hundred twenty-one thousand, seven hundred thirty".