261943089408 has 1728 divisors, whose sum is σ = 1113249392640. Its totient is φ = 58657996800.

The previous prime is 261943089347. The next prime is 261943089413. The reversal of 261943089408 is 804980349162.

It is a tau number, because it is divible by the number of its divisors (1728).

It is a super-2 number, since 2×261943089408² (a number of 24 digits) contains 22 as substring.

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 (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 1999565503 + ... + 1999565633.

Almost surely, 2^261943089408 is an apocalyptic number.

261943089408 is a gapful number since it is divisible by the number (28) 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 261943089408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (556624696320).

261943089408 is an abundant number, since it is smaller than the sum of its proper divisors (851306303232).

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

261943089408 is a wasteful number, since it uses less digits than its factorization.

261943089408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 221 (or 184 counting only the distinct ones).

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

The spelling of 261943089408 in words is "two hundred sixty-one billion, nine hundred forty-three million, eighty-nine thousand, four hundred eight".