1720005121 has 2 divisors, whose sum is σ = 1720005122. Its totient is φ = 1720005120.

The previous prime is 1720005103. The next prime is 1720005149. The reversal of 1720005121 is 1215000271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1576963521 + 143041600 = 39711^2 + 11960^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720005121 - 2²¹ = 1717907969 is a prime.

It is not a weakly prime, because it can be changed into another prime (1720005101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860002560 + 860002561.

It is an arithmetic number, because the mean of its divisors is an integer number (860002561).

Almost surely, 2^1720005121 is an apocalyptic number.

It is an amenable number.

1720005121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720005121 is an equidigital number, since it uses as much as digits as its factorization.

1720005121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 140, while the sum is 19.

The square root of 1720005121 is about 41472.9444457468. The cubic root of 1720005121 is about 1198.1464720674.

Adding to 1720005121 its reverse (1215000271), we get a palindrome (2935005392).

The spelling of 1720005121 in words is "one billion, seven hundred twenty million, five thousand, one hundred twenty-one".