81117473651 has 2 divisors, whose sum is σ = 81117473652. Its totient is φ = 81117473650.

The previous prime is 81117473611. The next prime is 81117473681. The reversal of 81117473651 is 15637471118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81117473651 - 2¹⁰ = 81117472627 is a prime.

It is not a weakly prime, because it can be changed into another prime (81117473611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40558736825 + 40558736826.

It is an arithmetic number, because the mean of its divisors is an integer number (40558736826).

Almost surely, 2^81117473651 is an apocalyptic number.

81117473651 is a deficient number, since it is larger than the sum of its proper divisors (1).

81117473651 is an equidigital number, since it uses as much as digits as its factorization.

81117473651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 141120, while the sum is 44.

The spelling of 81117473651 in words is "eighty-one billion, one hundred seventeen million, four hundred seventy-three thousand, six hundred fifty-one".