81919008947 has 2 divisors, whose sum is σ = 81919008948. Its totient is φ = 81919008946.

The previous prime is 81919008937. The next prime is 81919009013. The reversal of 81919008947 is 74980091918.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81919008947 - 2⁴ = 81919008931 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81919008892 and 81919008901.

It is not a weakly prime, because it can be changed into another prime (81919008907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40959504473 + 40959504474.

It is an arithmetic number, because the mean of its divisors is an integer number (40959504474).

Almost surely, 2^81919008947 is an apocalyptic number.

81919008947 is a deficient number, since it is larger than the sum of its proper divisors (1).

81919008947 is an equidigital number, since it uses as much as digits as its factorization.

81919008947 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1306368, while the sum is 56.

The spelling of 81919008947 in words is "eighty-one billion, nine hundred nineteen million, eight thousand, nine hundred forty-seven".