1561171320 has 80 divisors (see below), whose sum is σ = 5247281160. Its totient is φ = 416311488.

The previous prime is 1561171291. The next prime is 1561171321. The reversal of 1561171320 is 231711651.

1561171320 is a `hidden beast` number, since 1 + 561 + 1 + 71 + 32 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1561171321) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 237682 + ... + 244161.

Almost surely, 2^1561171320 is an apocalyptic number.

1561171320 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561171320 is an abundant number, since it is smaller than the sum of its proper divisors (3686109840).

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

1561171320 is a wasteful number, since it uses less digits than its factorization.

1561171320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 481866 (or 481853 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 27.

The square root of 1561171320 is about 39511.6605573595. The cubic root of 1561171320 is about 1160.0681985271.

Adding to 1561171320 its reverse (231711651), we get a palindrome (1792882971).

The spelling of 1561171320 in words is "one billion, five hundred sixty-one million, one hundred seventy-one thousand, three hundred twenty".