81953511 has 4 divisors (see below), whose sum is σ = 109271352. Its totient is φ = 54635672.

The previous prime is 81953471. The next prime is 81953513. The reversal of 81953511 is 11535918.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81953511 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81953513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13658916 + ... + 13658921.

It is an arithmetic number, because the mean of its divisors is an integer number (27317838).

Almost surely, 2^81953511 is an apocalyptic number.

81953511 is a deficient number, since it is larger than the sum of its proper divisors (27317841).

81953511 is a wasteful number, since it uses less digits than its factorization.

81953511 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27317840.

The product of its digits is 5400, while the sum is 33.

The square root of 81953511 is about 9052.8178486038. The cubic root of 81953511 is about 434.3660311866.

The spelling of 81953511 in words is "eighty-one million, nine hundred fifty-three thousand, five hundred eleven".