81681010 has 8 divisors (see below), whose sum is σ = 147025836. Its totient is φ = 32672400.

The previous prime is 81680999. The next prime is 81681011. The reversal of 81681010 is 1018618.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 79014321 + 2666689 = 8889^2 + 1633^2 .

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 (81681011) 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, 4084041 + ... + 4084060.

Almost surely, 2^81681010 is an apocalyptic number.

81681010 is a deficient number, since it is larger than the sum of its proper divisors (65344826).

81681010 is a wasteful number, since it uses less digits than its factorization.

81681010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8168108.

The product of its (nonzero) digits is 384, while the sum is 25.

The square root of 81681010 is about 9037.7546990389. The cubic root of 81681010 is about 433.8840643981.

Adding to 81681010 its reverse (1018618), we get a palindrome (82699628).

The spelling of 81681010 in words is "eighty-one million, six hundred eighty-one thousand, ten".