261896355840 has 480 divisors, whose sum is σ = 999556024320. Its totient is φ = 57250676736.

The previous prime is 261896355839. The next prime is 261896355871. The reversal of 261896355840 is 48553698162.

It is a tau number, because it is divible by the number of its divisors (480).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 39564051 + ... + 39570669.

It is an arithmetic number, because the mean of its divisors is an integer number (2082408384).

Almost surely, 2^261896355840 is an apocalyptic number.

261896355840 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 261896355840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (499778012160).

261896355840 is an abundant number, since it is smaller than the sum of its proper divisors (737659668480).

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

261896355840 is an equidigital number, since it uses as much as digits as its factorization.

261896355840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6685 (or 6659 counting only the distinct ones).

The product of its (nonzero) digits is 12441600, while the sum is 57.

The spelling of 261896355840 in words is "two hundred sixty-one billion, eight hundred ninety-six million, three hundred fifty-five thousand, eight hundred forty".