261540660 has 48 divisors (see below), whose sum is σ = 734078016. Its totient is φ = 69576192.

The previous prime is 261540623. The next prime is 261540661. The reversal of 261540660 is 66045162.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261540661) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20947 + ... + 31013.

It is an arithmetic number, because the mean of its divisors is an integer number (15293292).

Almost surely, 2^261540660 is an apocalyptic number.

261540660 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261540660 is an abundant number, since it is smaller than the sum of its proper divisors (472537356).

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

261540660 is a wasteful number, since it uses less digits than its factorization.

261540660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10512 (or 10510 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 30.

The square root of 261540660 is about 16172.2187717085. The cubic root of 261540660 is about 639.5086234806.

The spelling of 261540660 in words is "two hundred sixty-one million, five hundred forty thousand, six hundred sixty".