209145561941 has 18 divisors (see below), whose sum is σ = 218111606370. Its totient is φ = 200309578560.

The previous prime is 209145561893. The next prime is 209145561943. The reversal of 209145561941 is 149165541902.

It can be written as a sum of positive squares in 3 ways, for example, as 7046763025 + 202098798916 = 83945^2 + 449554^2 .

It is a de Polignac number, because none of the positive numbers 2^k-209145561941 is a prime.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209145561943) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 401430761 + ... + 401431281.

It is an arithmetic number, because the mean of its divisors is an integer number (12117311465).

Almost surely, 2^209145561941 is an apocalyptic number.

It is an amenable number.

209145561941 is a deficient number, since it is larger than the sum of its proper divisors (8966044429).

209145561941 is an frugal number, since it uses more digits than its factorization.

209145561941 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1397 (or 713 counting only the distinct ones).

The product of its (nonzero) digits is 388800, while the sum is 47.

It can be divided in two parts, 20914 and 5561941, that added together give a palindrome (5582855).

The spelling of 209145561941 in words is "two hundred nine billion, one hundred forty-five million, five hundred sixty-one thousand, nine hundred forty-one".