81439607890 has 16 divisors (see below), whose sum is σ = 155214311832. Its totient is φ = 30659617024.

The previous prime is 81439607881. The next prime is 81439607911. The reversal of 81439607890 is 9870693418.

It can be written as a sum of positive squares in 4 ways, for example, as 78979547089 + 2460060801 = 281033^2 + 49599^2 .

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, 239528089 + ... + 239528428.

Almost surely, 2^81439607890 is an apocalyptic number.

81439607890 is a deficient number, since it is larger than the sum of its proper divisors (73774703942).

81439607890 is a wasteful number, since it uses less digits than its factorization.

81439607890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 479056541.

The product of its (nonzero) digits is 2612736, while the sum is 55.

The spelling of 81439607890 in words is "eighty-one billion, four hundred thirty-nine million, six hundred seven thousand, eight hundred ninety".