691020020197 has 4 divisors (see below), whose sum is σ = 744175406380. Its totient is φ = 637864634016.

The previous prime is 691020020191. The next prime is 691020020209. The reversal of 691020020197 is 791020020196.

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

It can be written as a sum of positive squares in 2 ways, for example, as 30320908641 + 660699111556 = 174129^2 + 812834^2 .

It is a cyclic number.

It is not a de Polignac number, because 691020020197 - 2¹¹ = 691020018149 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 26577693072 + ... + 26577693097.

It is an arithmetic number, because the mean of its divisors is an integer number (186043851595).

Almost surely, 2^691020020197 is an apocalyptic number.

It is an amenable number.

691020020197 is a deficient number, since it is larger than the sum of its proper divisors (53155386183).

691020020197 is a wasteful number, since it uses less digits than its factorization.

691020020197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53155386182.

The product of its (nonzero) digits is 13608, while the sum is 37.

Subtracting 691020020197 from its reverse (791020020196), we obtain a palindrome (99999999999).

The spelling of 691020020197 in words is "six hundred ninety-one billion, twenty million, twenty thousand, one hundred ninety-seven".