81366009890 has 32 divisors (see below), whose sum is σ = 159785559360. Its totient is φ = 29585361600.

The previous prime is 81366009821. The next prime is 81366009937. The reversal of 81366009890 is 9890066318.

It is a super-3 number, since 3×81366009890³ (a number of 34 digits) contains 333 as substring.

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, 2184725 + ... + 2221655.

It is an arithmetic number, because the mean of its divisors is an integer number (4993298730).

Almost surely, 2^81366009890 is an apocalyptic number.

81366009890 is a deficient number, since it is larger than the sum of its proper divisors (78419549470).

81366009890 is a wasteful number, since it uses less digits than its factorization.

81366009890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56978.

The product of its (nonzero) digits is 559872, while the sum is 50.

The spelling of 81366009890 in words is "eighty-one billion, three hundred sixty-six million, nine thousand, eight hundred ninety".