261993813136 has 60 divisors (see below), whose sum is σ = 563257542960. Its totient is φ = 117046347840.

The previous prime is 261993813131. The next prime is 261993813161. The reversal of 261993813136 is 631318399162.

It is not an unprimeable number, because it can be changed into a prime (261993813131) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 52156321 + ... + 52161343.

It is an arithmetic number, because the mean of its divisors is an integer number (9387625716).

Almost surely, 2^261993813136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261993813136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (281628771480).

261993813136 is an abundant number, since it is smaller than the sum of its proper divisors (301263729824).

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

261993813136 is an frugal number, since it uses more digits than its factorization.

261993813136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10124 (or 5095 counting only the distinct ones).

The product of its digits is 1259712, while the sum is 52.

The spelling of 261993813136 in words is "two hundred sixty-one billion, nine hundred ninety-three million, eight hundred thirteen thousand, one hundred thirty-six".