261938880 has 448 divisors, whose sum is σ = 1088501760. Its totient is φ = 58060800.

The previous prime is 261938869. The next prime is 261938893. The reversal of 261938880 is 88839162.

261938880 is a `hidden beast` number, since 261 + 9 + 388 + 8 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a super-2 number, since 2×261938880² = 137223953711308800, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3689245 + ... + 3689315.

Almost surely, 2^261938880 is an apocalyptic number.

261938880 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 261938880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (544250880).

261938880 is an abundant number, since it is smaller than the sum of its proper divisors (826562880).

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

261938880 is a wasteful number, since it uses less digits than its factorization.

261938880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165 (or 149 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The square root of 261938880 is about 16184.5259430111. The cubic root of 261938880 is about 639.8330293592.

The spelling of 261938880 in words is "two hundred sixty-one million, nine hundred thirty-eight thousand, eight hundred eighty".