81181605146 has 32 divisors (see below), whose sum is σ = 131269254480. Its totient is φ = 37513728000.

The previous prime is 81181605139. The next prime is 81181605181. The reversal of 81181605146 is 64150618118.

It can be written as a sum of positive squares in 8 ways, for example, as 23866851121 + 57314754025 = 154489^2 + 239405^2 .

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1213910 + ... + 1279038.

Almost surely, 2^81181605146 is an apocalyptic number.

81181605146 is a deficient number, since it is larger than the sum of its proper divisors (50087649334).

81181605146 is a wasteful number, since it uses less digits than its factorization.

81181605146 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65810.

The product of its (nonzero) digits is 46080, while the sum is 41.

The spelling of 81181605146 in words is "eighty-one billion, one hundred eighty-one million, six hundred five thousand, one hundred forty-six".