81353857 has 8 divisors (see below), whose sum is σ = 92765736. Its totient is φ = 70678272.

The previous prime is 81353821. The next prime is 81353863. The reversal of 81353857 is 75835318.

It can be written as a sum of positive squares in 4 ways, for example, as 7376656 + 73977201 = 2716^2 + 8601^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81353857 - 2¹⁵ = 81321089 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81753857) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183838 + ... + 184279.

It is an arithmetic number, because the mean of its divisors is an integer number (11595717).

Almost surely, 2^81353857 is an apocalyptic number.

It is an amenable number.

81353857 is a deficient number, since it is larger than the sum of its proper divisors (11411879).

81353857 is a wasteful number, since it uses less digits than its factorization.

81353857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368147.

The product of its digits is 100800, while the sum is 40.

The square root of 81353857 is about 9019.6372986944. The cubic root of 81353857 is about 433.3040176749.

The spelling of 81353857 in words is "eighty-one million, three hundred fifty-three thousand, eight hundred fifty-seven".