261232821 has 6 divisors (see below), whose sum is σ = 377336310. Its totient is φ = 174155208.

The previous prime is 261232817. The next prime is 261232831. The reversal of 261232821 is 128232162.

261232821 is a `hidden beast` number, since 2 + 612 + 3 + 28 + 21 = 666.

261232821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 178222500 + 83010321 = 13350^2 + 9111^2 .

It is not a de Polignac number, because 261232821 - 2² = 261232817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261232831) 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, 14512926 + ... + 14512943.

It is an arithmetic number, because the mean of its divisors is an integer number (62889385).

Almost surely, 2^261232821 is an apocalyptic number.

It is an amenable number.

261232821 is a deficient number, since it is larger than the sum of its proper divisors (116103489).

261232821 is a wasteful number, since it uses less digits than its factorization.

261232821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29025875 (or 29025872 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 261232821 is about 16162.6984442574. The cubic root of 261232821 is about 639.2576198265.

Adding to 261232821 its reverse (128232162), we get a palindrome (389464983).

The spelling of 261232821 in words is "two hundred sixty-one million, two hundred thirty-two thousand, eight hundred twenty-one".