261131616 has 36 divisors (see below), whose sum is σ = 742593852. Its totient is φ = 87043776.

The previous prime is 261131609. The next prime is 261131617. The reversal of 261131616 is 616131162.

261131616 is a `hidden beast` number, since 2 + 6 + 11 + 31 + 616 = 666.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a self number, because there is not a number n which added to its sum of digits gives 261131616.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261131617) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 453066 + ... + 453641.

It is an arithmetic number, because the mean of its divisors is an integer number (20627607).

Almost surely, 2^261131616 is an apocalyptic number.

It is an amenable number.

261131616 is an abundant number, since it is smaller than the sum of its proper divisors (481462236).

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

261131616 is a wasteful number, since it uses less digits than its factorization.

261131616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906723 (or 906712 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 261131616 is about 16159.5673209402. The cubic root of 261131616 is about 639.1750569187.

Adding to 261131616 its reverse (616131162), we get a palindrome (877262778).

The spelling of 261131616 in words is "two hundred sixty-one million, one hundred thirty-one thousand, six hundred sixteen".