81661876 has 6 divisors (see below), whose sum is σ = 142908290. Its totient is φ = 40830936.

The previous prime is 81661837. The next prime is 81661901. The reversal of 81661876 is 67816618.

It can be written as a sum of positive squares in only one way, i.e., 77898276 + 3763600 = 8826^2 + 1940^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10207731 + ... + 10207738.

Almost surely, 2^81661876 is an apocalyptic number.

It is an amenable number.

81661876 is a deficient number, since it is larger than the sum of its proper divisors (61246414).

81661876 is a wasteful number, since it uses less digits than its factorization.

81661876 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20415473 (or 20415471 counting only the distinct ones).

The product of its digits is 96768, while the sum is 43.

The square root of 81661876 is about 9036.6960776602. The cubic root of 81661876 is about 433.8501822427.

The spelling of 81661876 in words is "eighty-one million, six hundred sixty-one thousand, eight hundred seventy-six".