720137609 has 2 divisors, whose sum is σ = 720137610. Its totient is φ = 720137608.

The previous prime is 720137557. The next prime is 720137611. The reversal of 720137609 is 906731027.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 407838025 + 312299584 = 20195^2 + 17672^2 .

It is an emirp because it is prime and its reverse (906731027) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 720137609 - 2²⁴ = 703360393 is a prime.

Together with 720137611, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (720137689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360068804 + 360068805.

It is an arithmetic number, because the mean of its divisors is an integer number (360068805).

Almost surely, 2^720137609 is an apocalyptic number.

It is an amenable number.

720137609 is a deficient number, since it is larger than the sum of its proper divisors (1).

720137609 is an equidigital number, since it uses as much as digits as its factorization.

720137609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15876, while the sum is 35.

The square root of 720137609 is about 26835.3797998091. The cubic root of 720137609 is about 896.3380458246.

The spelling of 720137609 in words is "seven hundred twenty million, one hundred thirty-seven thousand, six hundred nine".