261031005840 has 240 divisors, whose sum is σ = 901981519488. Its totient is φ = 62388480000.

The previous prime is 261031005811. The next prime is 261031005889. The reversal of 261031005840 is 48500130162.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-2 number, since 2×261031005840² (a number of 24 digits) contains 22 as substring.

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

It is a junction number, because it is equal to n+sod(n) for n = 261031005798 and 261031005807.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1998540 + ... + 2125140.

Almost surely, 2^261031005840 is an apocalyptic number.

261031005840 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 261031005840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (450990759744).

261031005840 is an abundant number, since it is smaller than the sum of its proper divisors (640950513648).

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

261031005840 is a wasteful number, since it uses less digits than its factorization.

261031005840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126710 (or 126693 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The spelling of 261031005840 in words is "two hundred sixty-one billion, thirty-one million, five thousand, eight hundred forty".