81121973 has 8 divisors (see below), whose sum is σ = 83119680. Its totient is φ = 79148160.

The previous prime is 81121967. The next prime is 81121981. The reversal of 81121973 is 37912118.

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 81121973 - 2¹⁸ = 80859829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81121933) 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, 998 + ... + 12776.

It is an arithmetic number, because the mean of its divisors is an integer number (10389960).

Almost surely, 2^81121973 is an apocalyptic number.

It is an amenable number.

81121973 is a deficient number, since it is larger than the sum of its proper divisors (1997707).

81121973 is a wasteful number, since it uses less digits than its factorization.

81121973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11947.

The product of its digits is 3024, while the sum is 32.

The square root of 81121973 is about 9006.7737287000. The cubic root of 81121973 is about 432.8919418088.

The spelling of 81121973 in words is "eighty-one million, one hundred twenty-one thousand, nine hundred seventy-three".