81545021770 has 16 divisors (see below), whose sum is σ = 150361065288. Its totient is φ = 31822447360.

The previous prime is 81545021717. The next prime is 81545021783. The reversal of 81545021770 is 7712054518.

It can be written as a sum of positive squares in 4 ways, for example, as 43806908601 + 37738113169 = 209301^2 + 194263^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 99444739 + ... + 99445558.

Almost surely, 2^81545021770 is an apocalyptic number.

81545021770 is a deficient number, since it is larger than the sum of its proper divisors (68816043518).

81545021770 is a wasteful number, since it uses less digits than its factorization.

81545021770 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198890345.

The product of its (nonzero) digits is 78400, while the sum is 40.

The spelling of 81545021770 in words is "eighty-one billion, five hundred forty-five million, twenty-one thousand, seven hundred seventy".