725686609 has 2 divisors, whose sum is σ = 725686610. Its totient is φ = 725686608.

The previous prime is 725686601. The next prime is 725686673. The reversal of 725686609 is 906686527.

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., 673558209 + 52128400 = 25953^2 + 7220^2 .

It is an emirp because it is prime and its reverse (906686527) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 725686609 - 2³ = 725686601 is a prime.

It is not a weakly prime, because it can be changed into another prime (725686601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 362843304 + 362843305.

It is an arithmetic number, because the mean of its divisors is an integer number (362843305).

Almost surely, 2^725686609 is an apocalyptic number.

It is an amenable number.

725686609 is a deficient number, since it is larger than the sum of its proper divisors (1).

725686609 is an equidigital number, since it uses as much as digits as its factorization.

725686609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1088640, while the sum is 49.

The square root of 725686609 is about 26938.5710274320. The cubic root of 725686609 is about 898.6343935672.

The spelling of 725686609 in words is "seven hundred twenty-five million, six hundred eighty-six thousand, six hundred nine".