81986182649 has 12 divisors (see below), whose sum is σ = 95397856884. Its totient is φ = 70254584064.

The previous prime is 81986182643. The next prime is 81986182667. The reversal of 81986182649 is 94628168918.

It can be written as a sum of positive squares in 2 ways, for example, as 36773815225 + 45212367424 = 191765^2 + 212632^2 .

It is not a de Polignac number, because 81986182649 - 2²⁴ = 81969405433 is a prime.

It is a Smith number, since the sum of its digits (62) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81986182591 and 81986182600.

It is not an unprimeable number, because it can be changed into a prime (81986182643) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47792 + ... + 407745.

It is an arithmetic number, because the mean of its divisors is an integer number (7949821407).

Almost surely, 2^81986182649 is an apocalyptic number.

It is an amenable number.

81986182649 is a deficient number, since it is larger than the sum of its proper divisors (13411674235).

81986182649 is a wasteful number, since it uses less digits than its factorization.

81986182649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459224 (or 459217 counting only the distinct ones).

The product of its digits is 11943936, while the sum is 62.

The spelling of 81986182649 in words is "eighty-one billion, nine hundred eighty-six million, one hundred eighty-two thousand, six hundred forty-nine".