198715787517891 has 48 divisors (see below), whose sum is σ = 323903751730944. Its totient is φ = 107913538789056.

The previous prime is 198715787517853. The next prime is 198715787517901.

198715787517891 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 198715787517891 - 2²¹ = 198715785420739 is a prime.

It is not an unprimeable number, because it can be changed into a prime (198715787517391) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 424595815 + ... + 425063568.

It is an arithmetic number, because the mean of its divisors is an integer number (6747994827728).

Almost surely, 2^{198715787517891} is an apocalyptic number.

198715787517891 is a deficient number, since it is larger than the sum of its proper divisors (125187964213053).

198715787517891 is a wasteful number, since it uses less digits than its factorization.

198715787517891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 849659480 (or 849659473 counting only the distinct ones).

The product of its digits is 2489356800, while the sum is 84.

The spelling of 198715787517891 in words is "one hundred ninety-eight trillion, seven hundred fifteen billion, seven hundred eighty-seven million, five hundred seventeen thousand, eight hundred ninety-one".