991657105547 has 4 divisors (see below), whose sum is σ = 991813796520. Its totient is φ = 991500414576.

The previous prime is 991657105529. The next prime is 991657105561. The reversal of 991657105547 is 745501756199.

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 991657105547 - 2³⁴ = 974477236363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991657105447) 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, 78335993 + ... + 78348650.

It is an arithmetic number, because the mean of its divisors is an integer number (247953449130).

Almost surely, 2^991657105547 is an apocalyptic number.

991657105547 is a deficient number, since it is larger than the sum of its proper divisors (156690973).

991657105547 is a wasteful number, since it uses less digits than its factorization.

991657105547 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 156690972.

The product of its (nonzero) digits is 11907000, while the sum is 59.

The spelling of 991657105547 in words is "nine hundred ninety-one billion, six hundred fifty-seven million, one hundred five thousand, five hundred forty-seven".