221306749 has 2 divisors, whose sum is σ = 221306750. Its totient is φ = 221306748.

The previous prime is 221306693. The next prime is 221306753. The reversal of 221306749 is 947603122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 216619524 + 4687225 = 14718^2 + 2165^2 .

It is a cyclic number.

It is not a de Polignac number, because 221306749 - 2⁹ = 221306237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (221306779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110653374 + 110653375.

It is an arithmetic number, because the mean of its divisors is an integer number (110653375).

Almost surely, 2^221306749 is an apocalyptic number.

It is an amenable number.

221306749 is a deficient number, since it is larger than the sum of its proper divisors (1).

221306749 is an equidigital number, since it uses as much as digits as its factorization.

221306749 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 18144, while the sum is 34.

The square root of 221306749 is about 14876.3822551049. The cubic root of 221306749 is about 604.8739568493.

The spelling of 221306749 in words is "two hundred twenty-one million, three hundred six thousand, seven hundred forty-nine".