1561277168 has 80 divisors (see below), whose sum is σ = 3455136000. Its totient is φ = 676515840.

The previous prime is 1561277143. The next prime is 1561277173. The reversal of 1561277168 is 8617721651.

It is a Cunningham number, because it is equal to 39513²-1.

It is a Harshad number since it is a multiple of its sum of digits (44).

Its product of digits (141120) is a multiple of the sum of its prime divisors (1344).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1817123 + ... + 1817981.

It is an arithmetic number, because the mean of its divisors is an integer number (43189200).

Almost surely, 2^1561277168 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1561277168, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1727568000).

1561277168 is an abundant number, since it is smaller than the sum of its proper divisors (1893858832).

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

1561277168 is a wasteful number, since it uses less digits than its factorization.

1561277168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1350 (or 1344 counting only the distinct ones).

The product of its digits is 141120, while the sum is 44.

The square root of 1561277168 is about 39512.9999873459. Note that the first 4 decimals coincide. The cubic root of 1561277168 is about 1160.0944156206.

The spelling of 1561277168 in words is "one billion, five hundred sixty-one million, two hundred seventy-seven thousand, one hundred sixty-eight".