81211983 has 4 divisors (see below), whose sum is σ = 108282648. Its totient is φ = 54141320.

The previous prime is 81211981. The next prime is 81211987. The reversal of 81211983 is 38911218.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81211983 - 2¹ = 81211981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81211981) 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, 13535328 + ... + 13535333.

It is an arithmetic number, because the mean of its divisors is an integer number (27070662).

Almost surely, 2^81211983 is an apocalyptic number.

81211983 is a deficient number, since it is larger than the sum of its proper divisors (27070665).

81211983 is a wasteful number, since it uses less digits than its factorization.

81211983 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27070664.

The product of its digits is 3456, while the sum is 33.

The square root of 81211983 is about 9011.7691381881. The cubic root of 81211983 is about 433.0519896967.

The spelling of 81211983 in words is "eighty-one million, two hundred eleven thousand, nine hundred eighty-three".