81572170 has 16 divisors (see below), whose sum is σ = 147224160. Its totient is φ = 32541264.

The previous prime is 81572167. The next prime is 81572201. The reversal of 81572170 is 7127518.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6972 + ... + 14551.

It is an arithmetic number, because the mean of its divisors is an integer number (9201510).

Almost surely, 2^81572170 is an apocalyptic number.

81572170 is a deficient number, since it is larger than the sum of its proper divisors (65651990).

81572170 is a wasteful number, since it uses less digits than its factorization.

81572170 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21909.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 81572170 is about 9031.7312847538. The cubic root of 81572170 is about 433.6912618016.

Adding to 81572170 its reverse (7127518), we get a palindrome (88699688).

The spelling of 81572170 in words is "eighty-one million, five hundred seventy-two thousand, one hundred seventy".