81218603 has 2 divisors, whose sum is σ = 81218604. Its totient is φ = 81218602.

The previous prime is 81218591. The next prime is 81218609. The reversal of 81218603 is 30681218.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81218603 - 2¹⁸ = 80956459 is a prime.

It is a super-2 number, since 2×81218603² = 13192922946543218, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81218609) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40609301 + 40609302.

It is an arithmetic number, because the mean of its divisors is an integer number (40609302).

Almost surely, 2^81218603 is an apocalyptic number.

81218603 is a deficient number, since it is larger than the sum of its proper divisors (1).

81218603 is an equidigital number, since it uses as much as digits as its factorization.

81218603 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 81218603 is about 9012.1364281728. The cubic root of 81218603 is about 433.0637561306.

The spelling of 81218603 in words is "eighty-one million, two hundred eighteen thousand, six hundred three".