1261581984 has 72 divisors (see below), whose sum is σ = 3863606292. Its totient is φ = 388177920.

The previous prime is 1261581953. The next prime is 1261582009. The reversal of 1261581984 is 4891851621.

It is a happy number.

1261581984 is a `hidden beast` number, since 1 + 2 + 61 + 581 + 9 + 8 + 4 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1173747600 + 87834384 = 34260^2 + 9372^2 .

It is a tau number, because it is divible by the number of its divisors (72).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 164737 + ... + 172224.

Almost surely, 2^1261581984 is an apocalyptic number.

It is an amenable number.

1261581984 is an abundant number, since it is smaller than the sum of its proper divisors (2602024308).

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

1261581984 is a wasteful number, since it uses less digits than its factorization.

1261581984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336990 (or 336979 counting only the distinct ones).

The product of its digits is 138240, while the sum is 45.

The square root of 1261581984 is about 35518.7553835998. The cubic root of 1261581984 is about 1080.5341390777.

The spelling of 1261581984 in words is "one billion, two hundred sixty-one million, five hundred eighty-one thousand, nine hundred eighty-four".