81853956321 has 4 divisors (see below), whose sum is σ = 109138608432. Its totient is φ = 54569304212.

The previous prime is 81853956287. The next prime is 81853956337. The reversal of 81853956321 is 12365935818.

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 81853956321 - 2²² = 81849762017 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81853956361) 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, 13642326051 + ... + 13642326056.

It is an arithmetic number, because the mean of its divisors is an integer number (27284652108).

Almost surely, 2^81853956321 is an apocalyptic number.

It is an amenable number.

81853956321 is a deficient number, since it is larger than the sum of its proper divisors (27284652111).

81853956321 is a wasteful number, since it uses less digits than its factorization.

81853956321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27284652110.

The product of its digits is 1555200, while the sum is 51.

The spelling of 81853956321 in words is "eighty-one billion, eight hundred fifty-three million, nine hundred fifty-six thousand, three hundred twenty-one".