81955918 has 16 divisors (see below), whose sum is σ = 134918784. Its totient is φ = 37027960.

The previous prime is 81955837. The next prime is 81955919.

81955918 is nontrivially palindromic in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81955919) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7480 + ... + 14827.

It is an arithmetic number, because the mean of its divisors is an integer number (8432424).

Almost surely, 2^81955918 is an apocalyptic number.

81955918 is a deficient number, since it is larger than the sum of its proper divisors (52962866).

81955918 is a wasteful number, since it uses less digits than its factorization.

81955918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22487.

The product of its digits is 129600, while the sum is 46.

The square root of 81955918 is about 9052.9507896597. The cubic root of 81955918 is about 434.3702836332.

The spelling of 81955918 in words is "eighty-one million, nine hundred fifty-five thousand, nine hundred eighteen".