810431981 has 2 divisors, whose sum is σ = 810431982. Its totient is φ = 810431980.

The previous prime is 810431969. The next prime is 810432001. The reversal of 810431981 is 189134018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 461863081 + 348568900 = 21491^2 + 18670^2 .

It is a cyclic number.

It is not a de Polignac number, because 810431981 - 2⁶ = 810431917 is a prime.

It is a super-2 number, since 2×810431981² = 1313599991655168722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (810430981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405215990 + 405215991.

It is an arithmetic number, because the mean of its divisors is an integer number (405215991).

Almost surely, 2^810431981 is an apocalyptic number.

It is an amenable number.

810431981 is a deficient number, since it is larger than the sum of its proper divisors (1).

810431981 is an equidigital number, since it uses as much as digits as its factorization.

810431981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 810431981 is about 28468.0870625337. The cubic root of 810431981 is about 932.3354341147.

Adding to 810431981 its reverse (189134018), we get a palindrome (999565999).

The spelling of 810431981 in words is "eight hundred ten million, four hundred thirty-one thousand, nine hundred eighty-one".