991380428 has 12 divisors (see below), whose sum is σ = 1794740640. Its totient is φ = 478597392.

The previous prime is 991380427. The next prime is 991380433. The reversal of 991380428 is 824083199.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (991380427) 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, 4273076 + ... + 4273307.

It is an arithmetic number, because the mean of its divisors is an integer number (149561720).

Almost surely, 2^991380428 is an apocalyptic number.

It is an amenable number.

991380428 is a deficient number, since it is larger than the sum of its proper divisors (803360212).

991380428 is a wasteful number, since it uses less digits than its factorization.

991380428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8546416 (or 8546414 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 44.

The square root of 991380428 is about 31486.1942444621. The cubic root of 991380428 is about 997.1185143487.

The spelling of 991380428 in words is "nine hundred ninety-one million, three hundred eighty thousand, four hundred twenty-eight".