991515847 has 8 divisors (see below), whose sum is σ = 1133424000. Its totient is φ = 849673464.

The previous prime is 991515841. The next prime is 991515913. The reversal of 991515847 is 748515199.

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 991515847 - 2³ = 991515839 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 991515847.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991515841) 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, 21804 + ... + 49582.

It is an arithmetic number, because the mean of its divisors is an integer number (141678000).

Almost surely, 2^991515847 is an apocalyptic number.

991515847 is a deficient number, since it is larger than the sum of its proper divisors (141908153).

991515847 is a wasteful number, since it uses less digits than its factorization.

991515847 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32885.

The product of its digits is 453600, while the sum is 49.

The square root of 991515847 is about 31488.3446214627. The cubic root of 991515847 is about 997.1639132157.

The spelling of 991515847 in words is "nine hundred ninety-one million, five hundred fifteen thousand, eight hundred forty-seven".