81218908 has 24 divisors (see below), whose sum is σ = 148705200. Its totient is φ = 38763648.

The previous prime is 81218897. The next prime is 81218927. The reversal of 81218908 is 80981218.

It is a super-2 number, since 2×81218908² = 13193022033424928, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6391 + ... + 14257.

It is an arithmetic number, because the mean of its divisors is an integer number (6196050).

Almost surely, 2^81218908 is an apocalyptic number.

It is an amenable number.

81218908 is a deficient number, since it is larger than the sum of its proper divisors (67486292).

81218908 is a wasteful number, since it uses less digits than its factorization.

81218908 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7989 (or 7987 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 37.

The square root of 81218908 is about 9012.1533497827. The cubic root of 81218908 is about 433.0642982243.

The spelling of 81218908 in words is "eighty-one million, two hundred eighteen thousand, nine hundred eight".