81970845 has 48 divisors (see below), whose sum is σ = 151811520. Its totient is φ = 37635840.

The previous prime is 81970843. The next prime is 81970879. The reversal of 81970845 is 54807918.

It is not a de Polignac number, because 81970845 - 2¹ = 81970843 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 81970797 and 81970806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81970841) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 33297 + ... + 35673.

It is an arithmetic number, because the mean of its divisors is an integer number (3162740).

Almost surely, 2^81970845 is an apocalyptic number.

It is an amenable number.

81970845 is a deficient number, since it is larger than the sum of its proper divisors (69840675).

81970845 is a wasteful number, since it uses less digits than its factorization.

81970845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2426 (or 2415 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 81970845 is about 9053.7751794486. The cubic root of 81970845 is about 434.3966533035.

The spelling of 81970845 in words is "eighty-one million, nine hundred seventy thousand, eight hundred forty-five".