91918199993 has 2 divisors, whose sum is σ = 91918199994. Its totient is φ = 91918199992.

The previous prime is 91918199953. The next prime is 91918200007. The reversal of 91918199993 is 39999181919.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 56364457744 + 35553742249 = 237412^2 + 188557^2 .

It is a cyclic number.

It is not a de Polignac number, because 91918199993 - 2¹⁰ = 91918198969 is a prime.

It is not a weakly prime, because it can be changed into another prime (91918199953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45959099996 + 45959099997.

It is an arithmetic number, because the mean of its divisors is an integer number (45959099997).

Almost surely, 2^91918199993 is an apocalyptic number.

It is an amenable number.

91918199993 is a deficient number, since it is larger than the sum of its proper divisors (1).

91918199993 is an equidigital number, since it uses as much as digits as its factorization.

91918199993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12754584, while the sum is 68.

The spelling of 91918199993 in words is "ninety-one billion, nine hundred eighteen million, one hundred ninety-nine thousand, nine hundred ninety-three".