81909976 has 8 divisors (see below), whose sum is σ = 153581220. Its totient is φ = 40954984.

The previous prime is 81909973. The next prime is 81909983. The reversal of 81909976 is 67990918.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81909973) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5119366 + ... + 5119381.

Almost surely, 2^81909976 is an apocalyptic number.

It is an amenable number.

81909976 is a deficient number, since it is larger than the sum of its proper divisors (71671244).

81909976 is a wasteful number, since it uses less digits than its factorization.

81909976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10238753 (or 10238749 counting only the distinct ones).

The product of its (nonzero) digits is 244944, while the sum is 49.

The square root of 81909976 is about 9050.4130292490. The cubic root of 81909976 is about 434.2891035301.

The spelling of 81909976 in words is "eighty-one million, nine hundred nine thousand, nine hundred seventy-six".