261441642138 has 32 divisors (see below), whose sum is σ = 535682028672. Its totient is φ = 85014451200.

The previous prime is 261441642103. The next prime is 261441642139. The reversal of 261441642138 is 831246144162.

It is a super-2 number, since 2×261441642138² (a number of 24 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 261441642138.

It is not an unprimeable number, because it can be changed into a prime (261441642139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3386395 + ... + 3462737.

It is an arithmetic number, because the mean of its divisors is an integer number (16740063396).

Almost surely, 2^261441642138 is an apocalyptic number.

261441642138 is an abundant number, since it is smaller than the sum of its proper divisors (274240386534).

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

261441642138 is a wasteful number, since it uses less digits than its factorization.

261441642138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90310.

The product of its digits is 221184, while the sum is 42.

The spelling of 261441642138 in words is "two hundred sixty-one billion, four hundred forty-one million, six hundred forty-two thousand, one hundred thirty-eight".