81972841 has 4 divisors (see below), whose sum is σ = 83716992. Its totient is φ = 80228692.

The previous prime is 81972833. The next prime is 81972853. The reversal of 81972841 is 14827918.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81972841 - 2³ = 81972833 is a prime.

It is a super-2 number, since 2×81972841² = 13439093323222562, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81972794 and 81972803.

It is not an unprimeable number, because it can be changed into a prime (81972811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 872005 + ... + 872098.

It is an arithmetic number, because the mean of its divisors is an integer number (20929248).

Almost surely, 2^81972841 is an apocalyptic number.

It is an amenable number.

81972841 is a deficient number, since it is larger than the sum of its proper divisors (1744151).

81972841 is a wasteful number, since it uses less digits than its factorization.

81972841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1744150.

The product of its digits is 32256, while the sum is 40.

The square root of 81972841 is about 9053.8854090385. The cubic root of 81972841 is about 434.4001791453.

The spelling of 81972841 in words is "eighty-one million, nine hundred seventy-two thousand, eight hundred forty-one".