81612245651 has 4 divisors (see below), whose sum is σ = 81701831904. Its totient is φ = 81522659400.

The previous prime is 81612245647. The next prime is 81612245681. The reversal of 81612245651 is 15654221618.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81612245651 - 2² = 81612245647 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81612245599 and 81612245608.

It is not an unprimeable number, because it can be changed into a prime (81612245641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44791760 + ... + 44793581.

It is an arithmetic number, because the mean of its divisors is an integer number (20425457976).

Almost surely, 2^81612245651 is an apocalyptic number.

81612245651 is a deficient number, since it is larger than the sum of its proper divisors (89586253).

81612245651 is an equidigital number, since it uses as much as digits as its factorization.

81612245651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89586252.

The product of its digits is 115200, while the sum is 41.

The spelling of 81612245651 in words is "eighty-one billion, six hundred twelve million, two hundred forty-five thousand, six hundred fifty-one".