81957107 has 4 divisors (see below), whose sum is σ = 81976416. Its totient is φ = 81937800.

The previous prime is 81957101. The next prime is 81957167. The reversal of 81957107 is 70175918.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 70175918 = 2 ⋅35087959.

It is a cyclic number.

It is not a de Polignac number, because 81957107 - 2⁴ = 81957091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81957101) 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 3 ways as a sum of consecutive naturals, for example, 203 + ... + 12804.

It is an arithmetic number, because the mean of its divisors is an integer number (20494104).

Almost surely, 2^81957107 is an apocalyptic number.

81957107 is a deficient number, since it is larger than the sum of its proper divisors (19309).

81957107 is a wasteful number, since it uses less digits than its factorization.

81957107 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19308.

The product of its (nonzero) digits is 17640, while the sum is 38.

The square root of 81957107 is about 9053.0164586175. The cubic root of 81957107 is about 434.3723842087.

The spelling of 81957107 in words is "eighty-one million, nine hundred fifty-seven thousand, one hundred seven".