195391155521 has 4 divisors (see below), whose sum is σ = 196635685332. Its totient is φ = 194146625712.

The previous prime is 195391155439. The next prime is 195391155527. The reversal of 195391155521 is 125551193591.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125551193591 = 9547 ⋅13150853.

It can be written as a sum of positive squares in 2 ways, for example, as 44816890000 + 150574265521 = 211700^2 + 388039^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-195391155521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (195391155527) 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, 622264670 + ... + 622264983.

It is an arithmetic number, because the mean of its divisors is an integer number (49158921333).

Almost surely, 2^195391155521 is an apocalyptic number.

It is an amenable number.

195391155521 is a deficient number, since it is larger than the sum of its proper divisors (1244529811).

195391155521 is a wasteful number, since it uses less digits than its factorization.

195391155521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1244529810.

The product of its digits is 303750, while the sum is 47.

The spelling of 195391155521 in words is "one hundred ninety-five billion, three hundred ninety-one million, one hundred fifty-five thousand, five hundred twenty-one".