261811872 has 192 divisors, whose sum is σ = 886152960. Its totient is φ = 73654272.

The previous prime is 261811867. The next prime is 261811873. The reversal of 261811872 is 278118162.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (261811873) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 441208 + ... + 441800.

It is an arithmetic number, because the mean of its divisors is an integer number (4615380).

Almost surely, 2^261811872 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261811872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (443076480).

261811872 is an abundant number, since it is smaller than the sum of its proper divisors (624341088).

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

261811872 is a wasteful number, since it uses less digits than its factorization.

261811872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 692 (or 678 counting only the distinct ones).

The product of its digits is 10752, while the sum is 36.

The square root of 261811872 is about 16180.6017193428. The cubic root of 261811872 is about 639.7295993132.

The spelling of 261811872 in words is "two hundred sixty-one million, eight hundred eleven thousand, eight hundred seventy-two".