261397558758 has 64 divisors (see below), whose sum is σ = 605438254080. Its totient is φ = 73693711872.

The previous prime is 261397558757. The next prime is 261397558817. The reversal of 261397558758 is 857855793162.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261397558753) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1748610 + ... + 1892202.

It is an arithmetic number, because the mean of its divisors is an integer number (9459972720).

Almost surely, 2^261397558758 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261397558758, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (302719127040).

261397558758 is an abundant number, since it is smaller than the sum of its proper divisors (344040695322).

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

261397558758 is a wasteful number, since it uses less digits than its factorization.

261397558758 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144181.

The product of its digits is 127008000, while the sum is 66.

The spelling of 261397558758 in words is "two hundred sixty-one billion, three hundred ninety-seven million, five hundred fifty-eight thousand, seven hundred fifty-eight".