81919946 has 4 divisors (see below), whose sum is σ = 122879922. Its totient is φ = 40959972.

The previous prime is 81919939. The next prime is 81919967. The reversal of 81919946 is 64991918.

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., 81090025 + 829921 = 9005^2 + 911^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81919946.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20479985 + ... + 20479988.

Almost surely, 2^81919946 is an apocalyptic number.

81919946 is a deficient number, since it is larger than the sum of its proper divisors (40959976).

81919946 is a wasteful number, since it uses less digits than its factorization.

81919946 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40959975.

The product of its digits is 139968, while the sum is 47.

The square root of 81919946 is about 9050.9638160806. The cubic root of 81919946 is about 434.3067232264.

The spelling of 81919946 in words is "eighty-one million, nine hundred nineteen thousand, nine hundred forty-six".