81973945 has 8 divisors (see below), whose sum is σ = 98919360. Its totient is φ = 65212080.

The previous prime is 81973937. The next prime is 81973993. The reversal of 81973945 is 54937918.

It is a happy number.

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

It is not a de Polignac number, because 81973945 - 2³ = 81973937 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81973895 and 81973904.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44901 + ... + 46690.

It is an arithmetic number, because the mean of its divisors is an integer number (12364920).

Almost surely, 2^81973945 is an apocalyptic number.

It is an amenable number.

81973945 is a deficient number, since it is larger than the sum of its proper divisors (16945415).

81973945 is a wasteful number, since it uses less digits than its factorization.

81973945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91775.

The product of its digits is 272160, while the sum is 46.

The square root of 81973945 is about 9053.9463771330. The cubic root of 81973945 is about 434.4021292857.

The spelling of 81973945 in words is "eighty-one million, nine hundred seventy-three thousand, nine hundred forty-five".