81643850601 has 8 divisors (see below), whose sum is σ = 108872933184. Its totient is φ = 54422000880.

The previous prime is 81643850551. The next prime is 81643850621. The reversal of 81643850601 is 10605834618.

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

It is not a de Polignac number, because 81643850601 - 2⁶ = 81643850537 is a prime.

It is a super-2 number, since 2×81643850601² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81643850621) 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, 1781821 + ... + 1827066.

It is an arithmetic number, because the mean of its divisors is an integer number (13609116648).

Almost surely, 2^81643850601 is an apocalyptic number.

It is an amenable number.

81643850601 is a deficient number, since it is larger than the sum of its proper divisors (27229082583).

81643850601 is a wasteful number, since it uses less digits than its factorization.

81643850601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3616431.

The product of its (nonzero) digits is 138240, while the sum is 42.

The spelling of 81643850601 in words is "eighty-one billion, six hundred forty-three million, eight hundred fifty thousand, six hundred one".