615661609 has 2 divisors, whose sum is σ = 615661610. Its totient is φ = 615661608.

The previous prime is 615661597. The next prime is 615661667. The reversal of 615661609 is 906166516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 608115600 + 7546009 = 24660^2 + 2747^2 .

It is a cyclic number.

It is not a de Polignac number, because 615661609 - 2⁵ = 615661577 is a prime.

It is not a weakly prime, because it can be changed into another prime (615661679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 307830804 + 307830805.

It is an arithmetic number, because the mean of its divisors is an integer number (307830805).

Almost surely, 2^615661609 is an apocalyptic number.

It is an amenable number.

615661609 is a deficient number, since it is larger than the sum of its proper divisors (1).

615661609 is an equidigital number, since it uses as much as digits as its factorization.

615661609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 58320, while the sum is 40.

The square root of 615661609 is about 24812.5292745419. The cubic root of 615661609 is about 850.7083410333.

The spelling of 615661609 in words is "six hundred fifteen million, six hundred sixty-one thousand, six hundred nine".