81854175621 has 16 divisors (see below), whose sum is σ = 111966918336. Its totient is φ = 53173454976.

The previous prime is 81854175581. The next prime is 81854175643. The reversal of 81854175621 is 12657145818.

It is not a de Polignac number, because 81854175621 - 2¹⁹ = 81853651333 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81854175521) 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, 2233410 + ... + 2269763.

It is an arithmetic number, because the mean of its divisors is an integer number (6997932396).

Almost surely, 2^81854175621 is an apocalyptic number.

It is an amenable number.

81854175621 is a deficient number, since it is larger than the sum of its proper divisors (30112742715).

81854175621 is a wasteful number, since it uses less digits than its factorization.

81854175621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4503332.

The product of its digits is 537600, while the sum is 48.

The spelling of 81854175621 in words is "eighty-one billion, eight hundred fifty-four million, one hundred seventy-five thousand, six hundred twenty-one".