81911254507 has 2 divisors, whose sum is σ = 81911254508. Its totient is φ = 81911254506.

The previous prime is 81911254471. The next prime is 81911254549. The reversal of 81911254507 is 70545211918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81911254507 - 2¹¹ = 81911252459 is a prime.

It is a super-2 number, since 2×81911254507² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81911254807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40955627253 + 40955627254.

It is an arithmetic number, because the mean of its divisors is an integer number (40955627254).

Almost surely, 2^81911254507 is an apocalyptic number.

81911254507 is a deficient number, since it is larger than the sum of its proper divisors (1).

81911254507 is an equidigital number, since it uses as much as digits as its factorization.

81911254507 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 100800, while the sum is 43.

The spelling of 81911254507 in words is "eighty-one billion, nine hundred eleven million, two hundred fifty-four thousand, five hundred seven".