261631104 has 128 divisors (see below), whose sum is σ = 801377280. Its totient is φ = 74081280.

The previous prime is 261631099. The next prime is 261631109. The reversal of 261631104 is 401136162.

It is an interprime number because it is at equal distance from previous prime (261631099) and next prime (261631109).

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (261631109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 351757 + ... + 352499.

It is an arithmetic number, because the mean of its divisors is an integer number (6260760).

Almost surely, 2^261631104 is an apocalyptic number.

261631104 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 261631104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (400688640).

261631104 is an abundant number, since it is smaller than the sum of its proper divisors (539746176).

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

261631104 is a wasteful number, since it uses less digits than its factorization.

261631104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 898 (or 886 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 261631104 is about 16175.0148067938. The cubic root of 261631104 is about 639.5823316528.

Adding to 261631104 its reverse (401136162), we get a palindrome (662767266).

The spelling of 261631104 in words is "two hundred sixty-one million, six hundred thirty-one thousand, one hundred four".