991556424 has 64 divisors (see below), whose sum is σ = 2765448000. Its totient is φ = 329184000.

The previous prime is 991556417. The next prime is 991556471. The reversal of 991556424 is 424655199.

991556424 is a `hidden beast` number, since 9 + 91 + 556 + 4 + 2 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 991556424.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45072 + ... + 63360.

It is an arithmetic number, because the mean of its divisors is an integer number (43210125).

Almost surely, 2^991556424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 991556424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1382724000).

991556424 is an abundant number, since it is smaller than the sum of its proper divisors (1773891576).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991556424 is a wasteful number, since it uses less digits than its factorization.

991556424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18555 (or 18545 counting only the distinct ones).

The product of its digits is 388800, while the sum is 45.

The square root of 991556424 is about 31488.9889326412. The cubic root of 991556424 is about 997.1775157443.

The spelling of 991556424 in words is "nine hundred ninety-one million, five hundred fifty-six thousand, four hundred twenty-four".