261542253520 has 20 divisors (see below), whose sum is σ = 608085739620. Its totient is φ = 104616901376.

The previous prime is 261542253517. The next prime is 261542253551. The reversal of 261542253520 is 25352245162.

It can be written as a sum of positive squares in 2 ways, for example, as 41547484224 + 219994769296 = 203832^2 + 469036^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a self number, because there is not a number n which added to its sum of digits gives 261542253520.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 1634639005 + ... + 1634639164.

It is an arithmetic number, because the mean of its divisors is an integer number (30404286981).

Almost surely, 2^261542253520 is an apocalyptic number.

261542253520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261542253520 is an abundant number, since it is smaller than the sum of its proper divisors (346543486100).

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

261542253520 is a wasteful number, since it uses less digits than its factorization.

261542253520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3269278182 (or 3269278176 counting only the distinct ones).

The product of its (nonzero) digits is 144000, while the sum is 37.

Adding to 261542253520 its reverse (25352245162), we get a palindrome (286894498682).

The spelling of 261542253520 in words is "two hundred sixty-one billion, five hundred forty-two million, two hundred fifty-three thousand, five hundred twenty".