81639551207 has 2 divisors, whose sum is σ = 81639551208. Its totient is φ = 81639551206.

The previous prime is 81639551167. The next prime is 81639551219. The reversal of 81639551207 is 70215593618.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81639551207 - 2¹⁸ = 81639289063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81639551297) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40819775603 + 40819775604.

It is an arithmetic number, because the mean of its divisors is an integer number (40819775604).

Almost surely, 2^81639551207 is an apocalyptic number.

81639551207 is a deficient number, since it is larger than the sum of its proper divisors (1).

81639551207 is an equidigital number, since it uses as much as digits as its factorization.

81639551207 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 453600, while the sum is 47.

The spelling of 81639551207 in words is "eighty-one billion, six hundred thirty-nine million, five hundred fifty-one thousand, two hundred seven".