81896818 has 4 divisors (see below), whose sum is σ = 122845230. Its totient is φ = 40948408.

The previous prime is 81896797. The next prime is 81896827. The reversal of 81896818 is 81869818.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81869818 = 2 ⋅40934909.

It can be written as a sum of positive squares in only one way, i.e., 53626329 + 28270489 = 7323^2 + 5317^2 .

81896818 is a strobogrammatic number because it is the same when read upside-down.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 20474203 + ... + 20474206.

Almost surely, 2^81896818 is an apocalyptic number.

81896818 is a deficient number, since it is larger than the sum of its proper divisors (40948412).

81896818 is a wasteful number, since it uses less digits than its factorization.

81896818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40948411.

The product of its digits is 221184, while the sum is 49.

The square root of 81896818 is about 9049.6860719033. The cubic root of 81896818 is about 434.2658475837.

Subtracting from 81896818 its reverse (81869818), we obtain a cube (27000 = 30³).

The spelling of 81896818 in words is "eighty-one million, eight hundred ninety-six thousand, eight hundred eighteen".