81556445051 has 2 divisors, whose sum is σ = 81556445052. Its totient is φ = 81556445050.

The previous prime is 81556445029. The next prime is 81556445057. The reversal of 81556445051 is 15054465518.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81556445051 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 81556444993 and 81556445011.

It is not a weakly prime, because it can be changed into another prime (81556445057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40778222525 + 40778222526.

It is an arithmetic number, because the mean of its divisors is an integer number (40778222526).

Almost surely, 2^81556445051 is an apocalyptic number.

81556445051 is a deficient number, since it is larger than the sum of its proper divisors (1).

81556445051 is an equidigital number, since it uses as much as digits as its factorization.

81556445051 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 480000, while the sum is 44.

The spelling of 81556445051 in words is "eighty-one billion, five hundred fifty-six million, four hundred forty-five thousand, fifty-one".