691020020195 has 4 divisors (see below), whose sum is σ = 829224024240. Its totient is φ = 552816016152.

The previous prime is 691020020191. The next prime is 691020020209. The reversal of 691020020195 is 591020020196.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 691020020195 - 2² = 691020020191 is a prime.

It is not an unprimeable number, because it can be changed into a prime (691020020191) 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, 69102002015 + ... + 69102002024.

It is an arithmetic number, because the mean of its divisors is an integer number (207306006060).

Almost surely, 2^691020020195 is an apocalyptic number.

691020020195 is a deficient number, since it is larger than the sum of its proper divisors (138204004045).

691020020195 is a wasteful number, since it uses less digits than its factorization.

691020020195 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 138204004044.

The product of its (nonzero) digits is 9720, while the sum is 35.

Subtracting from 691020020195 its reverse (591020020196), we obtain a palindrome (99999999999).

The spelling of 691020020195 in words is "six hundred ninety-one billion, twenty million, twenty thousand, one hundred ninety-five".