81214618 has 4 divisors (see below), whose sum is σ = 121821930. Its totient is φ = 40607308.

The previous prime is 81214613. The next prime is 81214631. The reversal of 81214618 is 81641218.

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

It can be written as a sum of positive squares in only one way, i.e., 73908409 + 7306209 = 8597^2 + 2703^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 81214618.

It is not an unprimeable number, because it can be changed into a prime (81214613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20303653 + ... + 20303656.

Almost surely, 2^81214618 is an apocalyptic number.

81214618 is a deficient number, since it is larger than the sum of its proper divisors (40607312).

81214618 is a wasteful number, since it uses less digits than its factorization.

81214618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40607311.

The product of its digits is 3072, while the sum is 31.

The square root of 81214618 is about 9011.9153347110. The cubic root of 81214618 is about 433.0566732406.

The spelling of 81214618 in words is "eighty-one million, two hundred fourteen thousand, six hundred eighteen".