661584761 has 2 divisors, whose sum is σ = 661584762. Its totient is φ = 661584760.

The previous prime is 661584757. The next prime is 661584797. The reversal of 661584761 is 167485166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 478253161 + 183331600 = 21869^2 + 13540^2 .

It is a cyclic number.

It is not a de Polignac number, because 661584761 - 2² = 661584757 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661584701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330792380 + 330792381.

It is an arithmetic number, because the mean of its divisors is an integer number (330792381).

Almost surely, 2^661584761 is an apocalyptic number.

It is an amenable number.

661584761 is a deficient number, since it is larger than the sum of its proper divisors (1).

661584761 is an equidigital number, since it uses as much as digits as its factorization.

661584761 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 241920, while the sum is 44.

The square root of 661584761 is about 25721.2900337444. The cubic root of 661584761 is about 871.3550737503.

The spelling of 661584761 in words is "six hundred sixty-one million, five hundred eighty-four thousand, seven hundred sixty-one".