2604688661 has 2 divisors, whose sum is σ = 2604688662. Its totient is φ = 2604688660.

The previous prime is 2604688637. The next prime is 2604688673. The reversal of 2604688661 is 1668864062.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1437168100 + 1167520561 = 37910^2 + 34169^2 .

It is a cyclic number.

It is not a de Polignac number, because 2604688661 - 2²⁶ = 2537579797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2604684661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1302344330 + 1302344331.

It is an arithmetic number, because the mean of its divisors is an integer number (1302344331).

Almost surely, 2^2604688661 is an apocalyptic number.

It is an amenable number.

2604688661 is a deficient number, since it is larger than the sum of its proper divisors (1).

2604688661 is an equidigital number, since it uses as much as digits as its factorization.

2604688661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 663552, while the sum is 47.

The square root of 2604688661 is about 51036.1505307757. The cubic root of 2604688661 is about 1375.8949388882.

The spelling of 2604688661 in words is "two billion, six hundred four million, six hundred eighty-eight thousand, six hundred sixty-one".