81006651 has 12 divisors (see below), whose sum is σ = 127647000. Its totient is φ = 49094880.

The previous prime is 81006637. The next prime is 81006661. The reversal of 81006651 is 15660018.

81006651 is a `hidden beast` number, since 8 + 1 + 0 + 0 + 6 + 651 = 666.

It is not a de Polignac number, because 81006651 - 2⁵ = 81006619 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81006661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 409026 + ... + 409223.

It is an arithmetic number, because the mean of its divisors is an integer number (10637250).

Almost surely, 2^81006651 is an apocalyptic number.

81006651 is a deficient number, since it is larger than the sum of its proper divisors (46640349).

81006651 is a wasteful number, since it uses less digits than its factorization.

81006651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 818266 (or 818263 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 81006651 is about 9000.3694924153. The cubic root of 81006651 is about 432.6867132396.

Adding to 81006651 its reverse (15660018), we get a palindrome (96666669).

The spelling of 81006651 in words is "eighty-one million, six thousand, six hundred fifty-one".