155840561 has 4 divisors (see below), whose sum is σ = 156084324. Its totient is φ = 155596800.

The previous prime is 155840533. The next prime is 155840563. The reversal of 155840561 is 165048551.

It is a happy number.

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 120318961 + 35521600 = 10969^2 + 5960^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-155840561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155840563) 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, 120920 + ... + 122201.

It is an arithmetic number, because the mean of its divisors is an integer number (39021081).

Almost surely, 2^155840561 is an apocalyptic number.

It is an amenable number.

155840561 is a deficient number, since it is larger than the sum of its proper divisors (243763).

155840561 is an equidigital number, since it uses as much as digits as its factorization.

155840561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243762.

The product of its (nonzero) digits is 24000, while the sum is 35.

The square root of 155840561 is about 12483.6116969409. The cubic root of 155840561 is about 538.1378025321.

The spelling of 155840561 in words is "one hundred fifty-five million, eight hundred forty thousand, five hundred sixty-one".