191385811553 has 4 divisors (see below), whose sum is σ = 193536214020. Its totient is φ = 189235409088.

The previous prime is 191385811469. The next prime is 191385811559. The reversal of 191385811553 is 355118583191.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 355118583191 = 17 ⋅20889328423.

It can be written as a sum of positive squares in 2 ways, for example, as 91474187809 + 99911623744 = 302447^2 + 316088^2 .

It is a cyclic number.

It is not a de Polignac number, because 191385811553 - 2¹⁴ = 191385795169 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191385811559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1075201100 + ... + 1075201277.

It is an arithmetic number, because the mean of its divisors is an integer number (48384053505).

Almost surely, 2^191385811553 is an apocalyptic number.

It is an amenable number.

191385811553 is a deficient number, since it is larger than the sum of its proper divisors (2150402467).

191385811553 is an equidigital number, since it uses as much as digits as its factorization.

191385811553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2150402466.

The product of its digits is 648000, while the sum is 50.

The spelling of 191385811553 in words is "one hundred ninety-one billion, three hundred eighty-five million, eight hundred eleven thousand, five hundred fifty-three".