31212161 has 2 divisors, whose sum is σ = 31212162. Its totient is φ = 31212160.

The previous prime is 31212143. The next prime is 31212163. The reversal of 31212161 is 16121213.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 29637136 + 1575025 = 5444^2 + 1255^2 .

It is a cyclic number.

It is not a de Polignac number, because 31212161 - 2¹⁰ = 31211137 is a prime.

Together with 31212163, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31212163) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606080 + 15606081.

It is an arithmetic number, because the mean of its divisors is an integer number (15606081).

Almost surely, 2^31212161 is an apocalyptic number.

It is an amenable number.

31212161 is a deficient number, since it is larger than the sum of its proper divisors (1).

31212161 is an equidigital number, since it uses as much as digits as its factorization.

31212161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72, while the sum is 17.

The square root of 31212161 is about 5586.7844955752. The cubic root of 31212161 is about 314.8530800534.

Adding to 31212161 its reverse (16121213), we get a palindrome (47333374).

The spelling of 31212161 in words is "thirty-one million, two hundred twelve thousand, one hundred sixty-one".