81953393 has 4 divisors (see below), whose sum is σ = 85516608. Its totient is φ = 78390180.

The previous prime is 81953351. The next prime is 81953411. The reversal of 81953393 is 39335918.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39335918 = 2 ⋅19667959.

It is a cyclic number.

It is not a de Polignac number, because 81953393 - 2⁶ = 81953329 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81953393.

It is not an unprimeable number, because it can be changed into a prime (81953293) 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 in 3 ways as a sum of consecutive naturals, for example, 1781573 + ... + 1781618.

It is an arithmetic number, because the mean of its divisors is an integer number (21379152).

Almost surely, 2^81953393 is an apocalyptic number.

It is an amenable number.

81953393 is a deficient number, since it is larger than the sum of its proper divisors (3563215).

81953393 is a wasteful number, since it uses less digits than its factorization.

81953393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3563214.

The product of its digits is 87480, while the sum is 41.

The square root of 81953393 is about 9052.8113312937. The cubic root of 81953393 is about 434.3658227138.

The spelling of 81953393 in words is "eighty-one million, nine hundred fifty-three thousand, three hundred ninety-three".