261247086540 has 576 divisors, whose sum is σ = 976649425920. Its totient is φ = 57379829760.

The previous prime is 261247086533. The next prime is 261247086557. The reversal of 261247086540 is 45680742162.

261247086540 is a `hidden beast` number, since 2 + 6 + 1 + 24 + 7 + 0 + 86 + 540 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 49317172 + ... + 49322468.

It is an arithmetic number, because the mean of its divisors is an integer number (1695571920).

Almost surely, 2^261247086540 is an apocalyptic number.

261247086540 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 261247086540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (488324712960).

261247086540 is an abundant number, since it is smaller than the sum of its proper divisors (715402339380).

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

261247086540 is a wasteful number, since it uses less digits than its factorization.

261247086540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5387 (or 5360 counting only the distinct ones).

The product of its (nonzero) digits is 645120, while the sum is 45.

The spelling of 261247086540 in words is "two hundred sixty-one billion, two hundred forty-seven million, eighty-six thousand, five hundred forty".