261311000 has 128 divisors (see below), whose sum is σ = 642470400. Its totient is φ = 99388800.

The previous prime is 261310993. The next prime is 261311077. The reversal of 261311000 is 113162.

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 31 ways as a sum of consecutive naturals, for example, 2536949 + ... + 2537051.

It is an arithmetic number, because the mean of its divisors is an integer number (5019300).

Almost surely, 2^261311000 is an apocalyptic number.

261311000 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 261311000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (321235200).

261311000 is an abundant number, since it is smaller than the sum of its proper divisors (381159400).

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

261311000 is a wasteful number, since it uses less digits than its factorization.

261311000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 226 (or 212 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 14.

The square root of 261311000 is about 16165.1167641932. The cubic root of 261311000 is about 639.3213835560.

Adding to 261311000 its reverse (113162), we get a palindrome (261424162).

The spelling of 261311000 in words is "two hundred sixty-one million, three hundred eleven thousand".