261981153792 has 240 divisors, whose sum is σ = 785412980352. Its totient is φ = 87180779520.

The previous prime is 261981153757. The next prime is 261981153803. The reversal of 261981153792 is 297351189162.

It is a happy number.

261981153792 is a `hidden beast` number, since 2 + 6 + 1 + 9 + 8 + 11 + 537 + 92 = 666.

261981153792 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 94679193 + ... + 94681959.

Almost surely, 2^261981153792 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261981153792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (392706490176).

261981153792 is an abundant number, since it is smaller than the sum of its proper divisors (523431826560).

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

261981153792 is an frugal number, since it uses more digits than its factorization.

261981153792 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3561 (or 3533 counting only the distinct ones).

The product of its digits is 1632960, while the sum is 54.

The spelling of 261981153792 in words is "two hundred sixty-one billion, nine hundred eighty-one million, one hundred fifty-three thousand, seven hundred ninety-two".