991838137 has 8 divisors (see below), whose sum is σ = 998464896. Its totient is φ = 985231632.

The previous prime is 991838119. The next prime is 991838207. The reversal of 991838137 is 731838199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991838137 - 2⁷ = 991838009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (991838737) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 100383 + ... + 109819.

It is an arithmetic number, because the mean of its divisors is an integer number (124808112).

Almost surely, 2^991838137 is an apocalyptic number.

It is an amenable number.

991838137 is a deficient number, since it is larger than the sum of its proper divisors (6626759).

991838137 is a wasteful number, since it uses less digits than its factorization.

991838137 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10127.

The product of its digits is 326592, while the sum is 49.

The square root of 991838137 is about 31493.4618135257. The cubic root of 991838137 is about 997.2719434753.

The spelling of 991838137 in words is "nine hundred ninety-one million, eight hundred thirty-eight thousand, one hundred thirty-seven".