261395680 has 144 divisors (see below), whose sum is σ = 764787744. Its totient is φ = 82667520.

The previous prime is 261395671. The next prime is 261395681. The reversal of 261395680 is 86593162.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261395681) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 188590 + ... + 189970.

It is an arithmetic number, because the mean of its divisors is an integer number (5311026).

Almost surely, 2^261395680 is an apocalyptic number.

261395680 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 261395680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (382393872).

261395680 is an abundant number, since it is smaller than the sum of its proper divisors (503392064).

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

261395680 is a wasteful number, since it uses less digits than its factorization.

261395680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1429 (or 1408 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 40.

The square root of 261395680 is about 16167.7357722100. The cubic root of 261395680 is about 639.3904352324.

The spelling of 261395680 in words is "two hundred sixty-one million, three hundred ninety-five thousand, six hundred eighty".