81120208531 has 2 divisors, whose sum is σ = 81120208532. Its totient is φ = 81120208530.

The previous prime is 81120208517. The next prime is 81120208537. The reversal of 81120208531 is 13580202118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81120208531 - 2²¹ = 81118111379 is a prime.

It is a super-2 number, since 2×81120208531² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81120208493 and 81120208502.

It is not a weakly prime, because it can be changed into another prime (81120208537) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40560104265 + 40560104266.

It is an arithmetic number, because the mean of its divisors is an integer number (40560104266).

Almost surely, 2^81120208531 is an apocalyptic number.

81120208531 is a deficient number, since it is larger than the sum of its proper divisors (1).

81120208531 is an equidigital number, since it uses as much as digits as its factorization.

81120208531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3840, while the sum is 31.

The spelling of 81120208531 in words is "eighty-one billion, one hundred twenty million, two hundred eight thousand, five hundred thirty-one".