261522144 has 144 divisors (see below), whose sum is σ = 836008992. Its totient is φ = 76944384.

The previous prime is 261522119. The next prime is 261522199. The reversal of 261522144 is 441225162.

261522144 is a `hidden beast` number, since 2 + 615 + 2 + 2 + 1 + 44 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

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, 84594 + ... + 87630.

It is an arithmetic number, because the mean of its divisors is an integer number (5805618).

Almost surely, 2^261522144 is an apocalyptic number.

261522144 is a gapful number since it is divisible by the number (24) 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 261522144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (418004496).

261522144 is an abundant number, since it is smaller than the sum of its proper divisors (574486848).

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

261522144 is a wasteful number, since it uses less digits than its factorization.

261522144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3089 (or 3078 counting only the distinct ones).

The product of its digits is 3840, while the sum is 27.

The square root of 261522144 is about 16171.6462983829. The cubic root of 261522144 is about 639.4935316001.

The spelling of 261522144 in words is "two hundred sixty-one million, five hundred twenty-two thousand, one hundred forty-four".