81998339650 has 12 divisors (see below), whose sum is σ = 152516911842. Its totient is φ = 32799335840.

The previous prime is 81998339639. The next prime is 81998339677. The reversal of 81998339650 is 5693389918.

It can be written as a sum of positive squares in 3 ways, for example, as 61333989649 + 20664350001 = 247657^2 + 143751^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 819983347 + ... + 819983446.

Almost surely, 2^81998339650 is an apocalyptic number.

81998339650 is a deficient number, since it is larger than the sum of its proper divisors (70518572192).

81998339650 is a wasteful number, since it uses less digits than its factorization.

81998339650 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639966805 (or 1639966800 counting only the distinct ones).

The product of its (nonzero) digits is 12597120, while the sum is 61.

The spelling of 81998339650 in words is "eighty-one billion, nine hundred ninety-eight million, three hundred thirty-nine thousand, six hundred fifty".