1561166556 has 12 divisors (see below), whose sum is σ = 3642721992. Its totient is φ = 520388848.

The previous prime is 1561166549. The next prime is 1561166669. The reversal of 1561166556 is 6556611651.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×1561166556² = 4874482031145802272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65048595 + ... + 65048618.

It is an arithmetic number, because the mean of its divisors is an integer number (303560166).

Almost surely, 2^1561166556 is an apocalyptic number.

It is an amenable number.

1561166556 is an abundant number, since it is smaller than the sum of its proper divisors (2081555436).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1561166556 is a wasteful number, since it uses less digits than its factorization.

1561166556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130097220 (or 130097218 counting only the distinct ones).

The product of its digits is 162000, while the sum is 42.

The square root of 1561166556 is about 39511.6002713127. The cubic root of 1561166556 is about 1160.0670185219.

The spelling of 1561166556 in words is "one billion, five hundred sixty-one million, one hundred sixty-six thousand, five hundred fifty-six".