261634256 has 80 divisors (see below), whose sum is σ = 579129600. Its totient is φ = 113508864.

The previous prime is 261634253. The next prime is 261634271. The reversal of 261634256 is 652436162.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261634253) 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 15 ways as a sum of consecutive naturals, for example, 944390 + ... + 944666.

It is an arithmetic number, because the mean of its divisors is an integer number (7239120).

Almost surely, 2^261634256 is an apocalyptic number.

261634256 is a gapful number since it is divisible by the number (26) 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 261634256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (289564800).

261634256 is an abundant number, since it is smaller than the sum of its proper divisors (317495344).

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

261634256 is a wasteful number, since it uses less digits than its factorization.

261634256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 556 (or 550 counting only the distinct ones).

The product of its digits is 51840, while the sum is 35.

The square root of 261634256 is about 16175.1122407234. The cubic root of 261634256 is about 639.5849000979.

The spelling of 261634256 in words is "two hundred sixty-one million, six hundred thirty-four thousand, two hundred fifty-six".