31818181973 has 2 divisors, whose sum is σ = 31818181974. Its totient is φ = 31818181972.

The previous prime is 31818181957. The next prime is 31818182017. The reversal of 31818181973 is 37918181813.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16811196964 + 15006985009 = 129658^2 + 122503^2 .

It is an emirp because it is prime and its reverse (37918181813) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31818181973 - 2⁴ = 31818181957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31818181933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15909090986 + 15909090987.

It is an arithmetic number, because the mean of its divisors is an integer number (15909090987).

Almost surely, 2^31818181973 is an apocalyptic number.

It is an amenable number.

31818181973 is a deficient number, since it is larger than the sum of its proper divisors (1).

31818181973 is an equidigital number, since it uses as much as digits as its factorization.

31818181973 is an evil number, because the sum of its binary digits is even.

The product of its digits is 290304, while the sum is 50.

The spelling of 31818181973 in words is "thirty-one billion, eight hundred eighteen million, one hundred eighty-one thousand, nine hundred seventy-three".