261204027840 has 672 divisors, whose sum is σ = 1067489579520. Its totient is φ = 57376677888.

The previous prime is 261204027839. The next prime is 261204027853. The reversal of 261204027840 is 48720402162.

261204027840 is a `hidden beast` number, since 26 + 120 + 402 + 78 + 40 = 666.

It is a tau number, because it is divible by the number of its divisors (672).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 261204027795 and 261204027804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 61909251 + ... + 61913469.

It is an arithmetic number, because the mean of its divisors is an integer number (1588526160).

Almost surely, 2^261204027840 is an apocalyptic number.

261204027840 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 261204027840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (533744789760).

261204027840 is an abundant number, since it is smaller than the sum of its proper divisors (806285551680).

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

261204027840 is a wasteful number, since it uses less digits than its factorization.

261204027840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4369 (or 4356 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 36.

The spelling of 261204027840 in words is "two hundred sixty-one billion, two hundred four million, twenty-seven thousand, eight hundred forty".