261506322120 has 128 divisors (see below), whose sum is σ = 791843817600. Its totient is φ = 69084524544.

The previous prime is 261506322089. The next prime is 261506322149. The reversal of 261506322120 is 21223605162.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 42154939 + ... + 42161141.

It is an arithmetic number, because the mean of its divisors is an integer number (6186279825).

Almost surely, 2^261506322120 is an apocalyptic number.

261506322120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261506322120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (395921908800).

261506322120 is an abundant number, since it is smaller than the sum of its proper divisors (530337495480).

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

261506322120 is a wasteful number, since it uses less digits than its factorization.

261506322120 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9439 (or 9435 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

Adding to 261506322120 its reverse (21223605162), we get a palindrome (282729927282).

The spelling of 261506322120 in words is "two hundred sixty-one billion, five hundred six million, three hundred twenty-two thousand, one hundred twenty".