261640992 has 48 divisors (see below), whose sum is σ = 708970752. Its totient is φ = 84399360.

The previous prime is 261640937. The next prime is 261640993. The reversal of 261640992 is 299046162.

It is a tau number, because it is divible by the number of its divisors (48).

It is a nialpdrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 261640992.

It is not an unprimeable number, because it can be changed into a prime (261640993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 40983 + ... + 46934.

It is an arithmetic number, because the mean of its divisors is an integer number (14770224).

Almost surely, 2^261640992 is an apocalyptic number.

It is an amenable number.

261640992 is an abundant number, since it is smaller than the sum of its proper divisors (447329760).

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

261640992 is a wasteful number, since it uses less digits than its factorization.

261640992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87961 (or 87953 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 39.

The square root of 261640992 is about 16175.3204605040. The cubic root of 261640992 is about 639.5903889394.

The spelling of 261640992 in words is "two hundred sixty-one million, six hundred forty thousand, nine hundred ninety-two".