261968361840 has 320 divisors, whose sum is σ = 941800970880. Its totient is φ = 66867240960.

The previous prime is 261968361839. The next prime is 261968361859. The reversal of 261968361840 is 48163869162.

261968361840 is a `hidden beast` number, since 2 + 6 + 19 + 6 + 8 + 3 + 618 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 4665774 + ... + 4721586.

It is an arithmetic number, because the mean of its divisors is an integer number (2943128034).

Almost surely, 2^261968361840 is an apocalyptic number.

261968361840 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 261968361840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (470900485440).

261968361840 is an abundant number, since it is smaller than the sum of its proper divisors (679832609040).

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

261968361840 is a wasteful number, since it uses less digits than its factorization.

261968361840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55929 (or 55917 counting only the distinct ones).

The product of its (nonzero) digits is 2985984, while the sum is 54.

The spelling of 261968361840 in words is "two hundred sixty-one billion, nine hundred sixty-eight million, three hundred sixty-one thousand, eight hundred forty".