81960857 has 4 divisors (see below), whose sum is σ = 89411856. Its totient is φ = 74509860.

The previous prime is 81960811. The next prime is 81960871. The reversal of 81960857 is 75806918.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 81960857 - 2¹⁶ = 81895321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81960157) 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, 3725483 + ... + 3725504.

It is an arithmetic number, because the mean of its divisors is an integer number (22352964).

Almost surely, 2^81960857 is an apocalyptic number.

It is an amenable number.

81960857 is a deficient number, since it is larger than the sum of its proper divisors (7450999).

81960857 is a wasteful number, since it uses less digits than its factorization.

81960857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7450998.

The product of its (nonzero) digits is 120960, while the sum is 44.

The square root of 81960857 is about 9053.2235695359. The cubic root of 81960857 is about 434.3790091033.

The spelling of 81960857 in words is "eighty-one million, nine hundred sixty thousand, eight hundred fifty-seven".