81805970 has 8 divisors (see below), whose sum is σ = 147250764. Its totient is φ = 32722384.

The previous prime is 81805967. The next prime is 81805973. The reversal of 81805970 is 7950818.

It is an interprime number because it is at equal distance from previous prime (81805967) and next prime (81805973).

It can be written as a sum of positive squares in 2 ways, for example, as 81558961 + 247009 = 9031^2 + 497^2 .

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

It is not an unprimeable number, because it can be changed into a prime (81805973) 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, 4090289 + ... + 4090308.

Almost surely, 2^81805970 is an apocalyptic number.

81805970 is a deficient number, since it is larger than the sum of its proper divisors (65444794).

81805970 is a wasteful number, since it uses less digits than its factorization.

81805970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8180604.

The product of its (nonzero) digits is 20160, while the sum is 38.

The square root of 81805970 is about 9044.6652784943. The cubic root of 81805970 is about 434.1052113842.

The spelling of 81805970 in words is "eighty-one million, eight hundred five thousand, nine hundred seventy".