261330440544 has 72 divisors (see below), whose sum is σ = 761284290312. Its totient is φ = 84985505280.

The previous prime is 261330440477. The next prime is 261330440549. The reversal of 261330440544 is 445044033162.

261330440544 is a `hidden beast` number, since 2 + 613 + 30 + 4 + 4 + 0 + 5 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a super-2 number, since 2×261330440544² (a number of 24 digits) contains 22 as substring.

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 = 261330440499 and 261330440508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261330440549) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 11054014 + ... + 11077629.

It is an arithmetic number, because the mean of its divisors is an integer number (10573392921).

Almost surely, 2^261330440544 is an apocalyptic number.

261330440544 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

261330440544 is an abundant number, since it is smaller than the sum of its proper divisors (499953849768).

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

261330440544 is a wasteful number, since it uses less digits than its factorization.

261330440544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22131700 (or 22131689 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 36.

The spelling of 261330440544 in words is "two hundred sixty-one billion, three hundred thirty million, four hundred forty thousand, five hundred forty-four".