81972887 has 8 divisors (see below), whose sum is σ = 82899600. Its totient is φ = 81051264.

The previous prime is 81972883. The next prime is 81972901. The reversal of 81972887 is 78827918.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81972887 - 2² = 81972883 is a prime.

It is a super-2 number, since 2×81972887² = 13439108406229538, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81972883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37439 + ... + 39567.

It is an arithmetic number, because the mean of its divisors is an integer number (10362450).

Almost surely, 2^81972887 is an apocalyptic number.

81972887 is a deficient number, since it is larger than the sum of its proper divisors (926713).

81972887 is a wasteful number, since it uses less digits than its factorization.

81972887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2545.

The product of its digits is 451584, while the sum is 50.

The square root of 81972887 is about 9053.8879493840. The cubic root of 81972887 is about 434.4002604015.

The spelling of 81972887 in words is "eighty-one million, nine hundred seventy-two thousand, eight hundred eighty-seven".