231784561 has 2 divisors, whose sum is σ = 231784562. Its totient is φ = 231784560.

The previous prime is 231784543. The next prime is 231784573. The reversal of 231784561 is 165487132.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 231648400 + 136161 = 15220^2 + 369^2 .

It is a cyclic number.

It is not a de Polignac number, because 231784561 - 2⁷ = 231784433 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 231784561.

It is not a weakly prime, because it can be changed into another prime (231784361) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115892280 + 115892281.

It is an arithmetic number, because the mean of its divisors is an integer number (115892281).

Almost surely, 2^231784561 is an apocalyptic number.

It is an amenable number.

231784561 is a deficient number, since it is larger than the sum of its proper divisors (1).

231784561 is an equidigital number, since it uses as much as digits as its factorization.

231784561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 37.

The square root of 231784561 is about 15224.4724374935. The cubic root of 231784561 is about 614.2731059840.

The spelling of 231784561 in words is "two hundred thirty-one million, seven hundred eighty-four thousand, five hundred sixty-one".