531231661 has 2 divisors, whose sum is σ = 531231662. Its totient is φ = 531231660.

The previous prime is 531231641. The next prime is 531231671. The reversal of 531231661 is 166132135.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 529460100 + 1771561 = 23010^2 + 1331^2 .

It is a cyclic number.

It is not a de Polignac number, because 531231661 - 2²⁷ = 397013933 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (531231601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 265615830 + 265615831.

It is an arithmetic number, because the mean of its divisors is an integer number (265615831).

Almost surely, 2^531231661 is an apocalyptic number.

It is an amenable number.

531231661 is a deficient number, since it is larger than the sum of its proper divisors (1).

531231661 is an equidigital number, since it uses as much as digits as its factorization.

531231661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 28.

The square root of 531231661 is about 23048.4633110323. The cubic root of 531231661 is about 809.8936308018.

Adding to 531231661 its reverse (166132135), we get a palindrome (697363796).

The spelling of 531231661 in words is "five hundred thirty-one million, two hundred thirty-one thousand, six hundred sixty-one".