261091680 has 96 divisors (see below), whose sum is σ = 829108224. Its totient is φ = 69060096.

The previous prime is 261091679. The next prime is 261091693. The reversal of 261091680 is 86190162.

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58819 + ... + 63101.

It is an arithmetic number, because the mean of its divisors is an integer number (8636544).

Almost surely, 2^261091680 is an apocalyptic number.

261091680 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 261091680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (414554112).

261091680 is an abundant number, since it is smaller than the sum of its proper divisors (568016544).

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

261091680 is a wasteful number, since it uses less digits than its factorization.

261091680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4428 (or 4420 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 261091680 is about 16158.3315970431. The cubic root of 261091680 is about 639.1424713119.

The spelling of 261091680 in words is "two hundred sixty-one million, ninety-one thousand, six hundred eighty".