261329540 has 24 divisors (see below), whose sum is σ = 554124480. Its totient is φ = 103516128.

The previous prime is 261329539. The next prime is 261329569. The reversal of 261329540 is 45923162.

It is a happy number.

It is a super-2 number, since 2×261329540² = 136586256953223200, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 261329497 and 261329506.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61370 + ... + 65489.

It is an arithmetic number, because the mean of its divisors is an integer number (23088520).

Almost surely, 2^261329540 is an apocalyptic number.

261329540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261329540 is an abundant number, since it is smaller than the sum of its proper divisors (292794940).

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

261329540 is a wasteful number, since it uses less digits than its factorization.

261329540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126971 (or 126969 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 261329540 is about 16165.6902110612. The cubic root of 261329540 is about 639.3365031365.

The spelling of 261329540 in words is "two hundred sixty-one million, three hundred twenty-nine thousand, five hundred forty".