261381996 has 18 divisors (see below), whose sum is σ = 660715692. Its totient is φ = 87127320.

The previous prime is 261381979. The next prime is 261381997. The reversal of 261381996 is 699183162.

It is a happy number.

261381996 is a `hidden beast` number, since 261 + 381 + 9 + 9 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is not an unprimeable number, because it can be changed into a prime (261381997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 3630270 + ... + 3630341.

Almost surely, 2^261381996 is an apocalyptic number.

It is an amenable number.

261381996 is an abundant number, since it is smaller than the sum of its proper divisors (399333696).

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

261381996 is a wasteful number, since it uses less digits than its factorization.

261381996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7260621 (or 7260616 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 261381996 is about 16167.3125781621. The cubic root of 261381996 is about 639.3792777267.

The spelling of 261381996 in words is "two hundred sixty-one million, three hundred eighty-one thousand, nine hundred ninety-six".