81995331386 has 4 divisors (see below), whose sum is σ = 122992997082. Its totient is φ = 40997665692.

The previous prime is 81995331331. The next prime is 81995331391. The reversal of 81995331386 is 68313359918.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 73858389361 + 8136942025 = 271769^2 + 90205^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20498832845 + ... + 20498832848.

Almost surely, 2^81995331386 is an apocalyptic number.

81995331386 is a deficient number, since it is larger than the sum of its proper divisors (40997665696).

81995331386 is a wasteful number, since it uses less digits than its factorization.

81995331386 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40997665695.

The product of its digits is 4199040, while the sum is 56.

The spelling of 81995331386 in words is "eighty-one billion, nine hundred ninety-five million, three hundred thirty-one thousand, three hundred eighty-six".