81929907 has 8 divisors (see below), whose sum is σ = 121377680. Its totient is φ = 54619920.

The previous prime is 81929899. The next prime is 81929909. The reversal of 81929907 is 70992918.

It is not a de Polignac number, because 81929907 - 2³ = 81929899 is a prime.

It is a super-2 number, since 2×81929907² = 13425019322057298, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81929909) by changing a digit.

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, 1517194 + ... + 1517247.

It is an arithmetic number, because the mean of its divisors is an integer number (15172210).

Almost surely, 2^81929907 is an apocalyptic number.

81929907 is a deficient number, since it is larger than the sum of its proper divisors (39447773).

81929907 is a wasteful number, since it uses less digits than its factorization.

81929907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3034450 (or 3034444 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 81929907 is about 9051.5140722423. The cubic root of 81929907 is about 434.3243255897.

The spelling of 81929907 in words is "eighty-one million, nine hundred twenty-nine thousand, nine hundred seven".