81545973 has 4 divisors (see below), whose sum is σ = 108727968. Its totient is φ = 54363980.

The previous prime is 81545969. The next prime is 81545977. The reversal of 81545973 is 37954518.

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 an interprime number because it is at equal distance from previous prime (81545969) and next prime (81545977).

It is a cyclic number.

It is not a de Polignac number, because 81545973 - 2² = 81545969 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81545977) 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, 13590993 + ... + 13590998.

It is an arithmetic number, because the mean of its divisors is an integer number (27181992).

Almost surely, 2^81545973 is an apocalyptic number.

It is an amenable number.

81545973 is a deficient number, since it is larger than the sum of its proper divisors (27181995).

81545973 is a wasteful number, since it uses less digits than its factorization.

81545973 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27181994.

The product of its digits is 151200, while the sum is 42.

The square root of 81545973 is about 9030.2808926412. The cubic root of 81545973 is about 433.6448300082.

The spelling of 81545973 in words is "eighty-one million, five hundred forty-five thousand, nine hundred seventy-three".