1561361640 has 32 divisors (see below), whose sum is σ = 4684085280. Its totient is φ = 416363072.

The previous prime is 1561361629. The next prime is 1561361677. The reversal of 1561361640 is 461631651.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6505554 + ... + 6505793.

It is an arithmetic number, because the mean of its divisors is an integer number (146377665).

Almost surely, 2^1561361640 is an apocalyptic number.

1561361640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1561361640 is an abundant number, since it is smaller than the sum of its proper divisors (3122723640).

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

1561361640 is a wasteful number, since it uses less digits than its factorization.

1561361640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13011361 (or 13011357 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The square root of 1561361640 is about 39514.0688869167. The cubic root of 1561361640 is about 1160.1153373229.

The spelling of 1561361640 in words is "one billion, five hundred sixty-one million, three hundred sixty-one thousand, six hundred forty".