261805140179856 has 640 divisors, whose sum is σ = 955911831060480. Its totient is φ = 66737526220800.

The previous prime is 261805140179839. The next prime is 261805140179881. The reversal of 261805140179856 is 658971041508162.

261805140179856 is a `hidden beast` number, since 2 + 6 + 1 + 80 + 5 + 1 + 401 + 79 + 85 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 261805140179793 and 261805140179802.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 988210546 + ... + 988475438.

It is an arithmetic number, because the mean of its divisors is an integer number (1493612236032).

Almost surely, 2^{261805140179856} is an apocalyptic number.

261805140179856 is a gapful number since it is divisible by the number (26) 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 261805140179856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (477955915530240).

261805140179856 is an abundant number, since it is smaller than the sum of its proper divisors (694106690880624).

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

261805140179856 is a wasteful number, since it uses less digits than its factorization.

261805140179856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265772 (or 265760 counting only the distinct ones).

The product of its (nonzero) digits is 29030400, while the sum is 63.

The spelling of 261805140179856 in words is "two hundred sixty-one trillion, eight hundred five billion, one hundred forty million, one hundred seventy-nine thousand, eight hundred fifty-six".