1905121607917 has 6 divisors (see below), whose sum is σ = 2094059288174. Its totient is φ = 1731928734360.

The previous prime is 1905121607897. The next prime is 1905121607923. The reversal of 1905121607917 is 7197061215091.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 1709279071236 + 195842536681 = 1307394^2 + 442541^2 .

It is a de Polignac number, because none of the positive numbers 2^k-1905121607917 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 (1905121605917) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7872403218 + ... + 7872403459.

Almost surely, 2^{1905121607917} is an apocalyptic number.

It is an amenable number.

1905121607917 is a deficient number, since it is larger than the sum of its proper divisors (188937680257).

1905121607917 is a wasteful number, since it uses less digits than its factorization.

1905121607917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15744806699 (or 15744806688 counting only the distinct ones).

The product of its (nonzero) digits is 238140, while the sum is 49.

The spelling of 1905121607917 in words is "one trillion, nine hundred five billion, one hundred twenty-one million, six hundred seven thousand, nine hundred seventeen".