155564561 has 2 divisors, whose sum is σ = 155564562. Its totient is φ = 155564560.

The previous prime is 155564557. The next prime is 155564567. The reversal of 155564561 is 165465551.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 130873600 + 24690961 = 11440^2 + 4969^2 .

It is a cyclic number.

It is not a de Polignac number, because 155564561 - 2² = 155564557 is a prime.

It is not a weakly prime, because it can be changed into another prime (155564567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77782280 + 77782281.

It is an arithmetic number, because the mean of its divisors is an integer number (77782281).

Almost surely, 2^155564561 is an apocalyptic number.

It is an amenable number.

155564561 is a deficient number, since it is larger than the sum of its proper divisors (1).

155564561 is an equidigital number, since it uses as much as digits as its factorization.

155564561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90000, while the sum is 38.

The square root of 155564561 is about 12472.5523049615. The cubic root of 155564561 is about 537.8199267903.

The spelling of 155564561 in words is "one hundred fifty-five million, five hundred sixty-four thousand, five hundred sixty-one".