155500661 has 2 divisors, whose sum is σ = 155500662. Its totient is φ = 155500660.

The previous prime is 155500643. The next prime is 155500663. The reversal of 155500661 is 166005551.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 125305636 + 30195025 = 11194^2 + 5495^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155500661 is a prime.

It is a Sophie Germain prime.

Together with 155500663, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155500663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77750330 + 77750331.

It is an arithmetic number, because the mean of its divisors is an integer number (77750331).

Almost surely, 2^155500661 is an apocalyptic number.

It is an amenable number.

155500661 is a deficient number, since it is larger than the sum of its proper divisors (1).

155500661 is an equidigital number, since it uses as much as digits as its factorization.

155500661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4500, while the sum is 29.

The square root of 155500661 is about 12469.9904169971. The cubic root of 155500661 is about 537.7462780542.

The spelling of 155500661 in words is "one hundred fifty-five million, five hundred thousand, six hundred sixty-one".