81071011421 has 2 divisors, whose sum is σ = 81071011422. Its totient is φ = 81071011420.

The previous prime is 81071011361. The next prime is 81071011453. The reversal of 81071011421 is 12411017018.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 41672731321 + 39398280100 = 204139^2 + 198490^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81071011421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81071011481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40535505710 + 40535505711.

It is an arithmetic number, because the mean of its divisors is an integer number (40535505711).

Almost surely, 2^81071011421 is an apocalyptic number.

It is an amenable number.

81071011421 is a deficient number, since it is larger than the sum of its proper divisors (1).

81071011421 is an equidigital number, since it uses as much as digits as its factorization.

81071011421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 26.

Adding to 81071011421 its reverse (12411017018), we get a palindrome (93482028439).

The spelling of 81071011421 in words is "eighty-one billion, seventy-one million, eleven thousand, four hundred twenty-one".