1721656289 has 2 divisors, whose sum is σ = 1721656290. Its totient is φ = 1721656288.

The previous prime is 1721656267. The next prime is 1721656373. The reversal of 1721656289 is 9826561271.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1721586064 + 70225 = 41492^2 + 265^2 .

It is an emirp because it is prime and its reverse (9826561271) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721656289 is a prime.

It is not a weakly prime, because it can be changed into another prime (1721656229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860828144 + 860828145.

It is an arithmetic number, because the mean of its divisors is an integer number (860828145).

Almost surely, 2^1721656289 is an apocalyptic number.

It is an amenable number.

1721656289 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721656289 is an equidigital number, since it uses as much as digits as its factorization.

1721656289 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 47.

The square root of 1721656289 is about 41492.8462388398. The cubic root of 1721656289 is about 1198.5297477472.

The spelling of 1721656289 in words is "one billion, seven hundred twenty-one million, six hundred fifty-six thousand, two hundred eighty-nine".