81671635293 has 4 divisors (see below), whose sum is σ = 108895513728. Its totient is φ = 54447756860.

The previous prime is 81671635271. The next prime is 81671635319. The reversal of 81671635293 is 39253617618.

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 81671635293 - 2¹⁶ = 81671569757 is a prime.

It is a super-2 number, since 2×81671635293² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81671635393) 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, 13611939213 + ... + 13611939218.

It is an arithmetic number, because the mean of its divisors is an integer number (27223878432).

Almost surely, 2^81671635293 is an apocalyptic number.

It is an amenable number.

81671635293 is a deficient number, since it is larger than the sum of its proper divisors (27223878435).

81671635293 is a wasteful number, since it uses less digits than its factorization.

81671635293 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27223878434.

The product of its digits is 1632960, while the sum is 51.

The spelling of 81671635293 in words is "eighty-one billion, six hundred seventy-one million, six hundred thirty-five thousand, two hundred ninety-three".