81936657 has 16 divisors (see below), whose sum is σ = 132423360. Its totient is φ = 49658400.

The previous prime is 81936643. The next prime is 81936671. The reversal of 81936657 is 75663918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81936643) and next prime (81936671).

It is not a de Polignac number, because 81936657 - 2⁷ = 81936529 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81936637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 137644 + ... + 138237.

It is an arithmetic number, because the mean of its divisors is an integer number (8276460).

Almost surely, 2^81936657 is an apocalyptic number.

It is an amenable number.

81936657 is a deficient number, since it is larger than the sum of its proper divisors (50486703).

81936657 is a wasteful number, since it uses less digits than its factorization.

81936657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 275901 (or 275895 counting only the distinct ones).

The product of its digits is 272160, while the sum is 45.

The square root of 81936657 is about 9051.8869303588. The cubic root of 81936657 is about 434.3362528935.

The spelling of 81936657 in words is "eighty-one million, nine hundred thirty-six thousand, six hundred fifty-seven".