155000561 has 4 divisors (see below), whose sum is σ = 155896692. Its totient is φ = 154104432.

The previous prime is 155000557. The next prime is 155000581. The reversal of 155000561 is 165000551.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 121000000 + 34000561 = 11000^2 + 5831^2 .

It is a cyclic number.

It is not a de Polignac number, because 155000561 - 2² = 155000557 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155000581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 447806 + ... + 448151.

It is an arithmetic number, because the mean of its divisors is an integer number (38974173).

Almost surely, 2^155000561 is an apocalyptic number.

It is an amenable number.

155000561 is a deficient number, since it is larger than the sum of its proper divisors (896131).

155000561 is an equidigital number, since it uses as much as digits as its factorization.

155000561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 896130.

The product of its (nonzero) digits is 750, while the sum is 23.

The square root of 155000561 is about 12449.9221282705. The cubic root of 155000561 is about 537.1691835615.

The spelling of 155000561 in words is "one hundred fifty-five million, five hundred sixty-one", and thus it is an aban number.