1555005561 has 4 divisors (see below), whose sum is σ = 2073340752. Its totient is φ = 1036670372.

The previous prime is 1555005553. The next prime is 1555005587. The reversal of 1555005561 is 1655005551.

1555005561 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1555005561 - 2³ = 1555005553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1555005511) 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, 259167591 + ... + 259167596.

It is an arithmetic number, because the mean of its divisors is an integer number (518335188).

Almost surely, 2^1555005561 is an apocalyptic number.

It is an amenable number.

1555005561 is a deficient number, since it is larger than the sum of its proper divisors (518335191).

1555005561 is an equidigital number, since it uses as much as digits as its factorization.

1555005561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 518335190.

The product of its (nonzero) digits is 18750, while the sum is 33.

The square root of 1555005561 is about 39433.5588173322. The cubic root of 1555005561 is about 1158.5389753604.

The spelling of 1555005561 in words is "one billion, five hundred fifty-five million, five thousand, five hundred sixty-one".