1720542221 has 2 divisors, whose sum is σ = 1720542222. Its totient is φ = 1720542220.

The previous prime is 1720542193. The next prime is 1720542227. The reversal of 1720542221 is 1222450271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1696286596 + 24255625 = 41186^2 + 4925^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720542221 - 2¹⁸ = 1720280077 is a prime.

It is a super-2 number, since 2×1720542221² = 5920531068487225682, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1720542227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860271110 + 860271111.

It is an arithmetic number, because the mean of its divisors is an integer number (860271111).

Almost surely, 2^1720542221 is an apocalyptic number.

It is an amenable number.

1720542221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720542221 is an equidigital number, since it uses as much as digits as its factorization.

1720542221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2240, while the sum is 26.

The square root of 1720542221 is about 41479.4192461756. The cubic root of 1720542221 is about 1198.2711727616.

Adding to 1720542221 its reverse (1222450271), we get a palindrome (2942992492).

The spelling of 1720542221 in words is "one billion, seven hundred twenty million, five hundred forty-two thousand, two hundred twenty-one".