261265680 has 240 divisors, whose sum is σ = 957605376. Its totient is φ = 63452160.

The previous prime is 261265679. The next prime is 261265687. The reversal of 261265680 is 86562162.

It is a tau number, because it is divible by the number of its divisors (240).

It is a super-3 number, since 3×261265680³ (a number of 26 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (261265687) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 963945 + ... + 964215.

Almost surely, 2^261265680 is an apocalyptic number.

261265680 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261265680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (478802688).

261265680 is an abundant number, since it is smaller than the sum of its proper divisors (696339696).

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

261265680 is a wasteful number, since it uses less digits than its factorization.

261265680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 406 (or 397 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 261265680 is about 16163.7149195351. The cubic root of 261265680 is about 639.2844215703.

The spelling of 261265680 in words is "two hundred sixty-one million, two hundred sixty-five thousand, six hundred eighty".