991331424 has 36 divisors (see below), whose sum is σ = 2819099556. Its totient is φ = 330443712.

The previous prime is 991331377. The next prime is 991331437. The reversal of 991331424 is 424133199.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1720774 + ... + 1721349.

It is an arithmetic number, because the mean of its divisors is an integer number (78308321).

Almost surely, 2^991331424 is an apocalyptic number.

It is an amenable number.

991331424 is an abundant number, since it is smaller than the sum of its proper divisors (1827768132).

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

991331424 is a wasteful number, since it uses less digits than its factorization.

991331424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3442139 (or 3442128 counting only the distinct ones).

The product of its digits is 23328, while the sum is 36.

The square root of 991331424 is about 31485.4160525155. The cubic root of 991331424 is about 997.1020848667.

The spelling of 991331424 in words is "nine hundred ninety-one million, three hundred thirty-one thousand, four hundred twenty-four".