1720661251949 has 2 divisors, whose sum is σ = 1720661251950. Its totient is φ = 1720661251948.

The previous prime is 1720661251909. The next prime is 1720661251961. The reversal of 1720661251949 is 9491521660271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1718608255849 + 2052996100 = 1310957^2 + 45310^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1720661251949 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1720661251949.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1720661251909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860330625974 + 860330625975.

It is an arithmetic number, because the mean of its divisors is an integer number (860330625975).

Almost surely, 2^{1720661251949} is an apocalyptic number.

It is an amenable number.

1720661251949 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720661251949 is an equidigital number, since it uses as much as digits as its factorization.

1720661251949 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1632960, while the sum is 53.

The spelling of 1720661251949 in words is "one trillion, seven hundred twenty billion, six hundred sixty-one million, two hundred fifty-one thousand, nine hundred forty-nine".