81953819 has 2 divisors, whose sum is σ = 81953820. Its totient is φ = 81953818.

The previous prime is 81953771. The next prime is 81953831. The reversal of 81953819 is 91835918.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81953819 - 2²⁴ = 65176603 is a prime.

It is a super-2 number, since 2×81953819² = 13432856897369522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81953819.

It is not a weakly prime, because it can be changed into another prime (81953849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40976909 + 40976910.

It is an arithmetic number, because the mean of its divisors is an integer number (40976910).

Almost surely, 2^81953819 is an apocalyptic number.

81953819 is a deficient number, since it is larger than the sum of its proper divisors (1).

81953819 is an equidigital number, since it uses as much as digits as its factorization.

81953819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 77760, while the sum is 44.

The square root of 81953819 is about 9052.8348598657. The cubic root of 81953819 is about 434.3665753348.

The spelling of 81953819 in words is "eighty-one million, nine hundred fifty-three thousand, eight hundred nineteen".