261505606379 has 8 divisors (see below), whose sum is σ = 272885696160. Its totient is φ = 250126373376.

The previous prime is 261505606339. The next prime is 261505606381. The reversal of 261505606379 is 973606505162.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 261505606379 - 2¹² = 261505602283 is a prime.

It is a super-3 number, since 3×261505606379³ (a number of 35 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261505606339) 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 7 ways as a sum of consecutive naturals, for example, 453899 + ... + 853835.

It is an arithmetic number, because the mean of its divisors is an integer number (34110712020).

Almost surely, 2^261505606379 is an apocalyptic number.

261505606379 is a deficient number, since it is larger than the sum of its proper divisors (11380089781).

261505606379 is a wasteful number, since it uses less digits than its factorization.

261505606379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 428389.

The product of its (nonzero) digits is 2041200, while the sum is 50.

The spelling of 261505606379 in words is "two hundred sixty-one billion, five hundred five million, six hundred six thousand, three hundred seventy-nine".