991555445 has 8 divisors (see below), whose sum is σ = 1207626144. Its totient is φ = 781404624.

The previous prime is 991555441. The next prime is 991555457. The reversal of 991555445 is 544555199.

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 991555445 - 2² = 991555441 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 991555445.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991555441) 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, 1479599 + ... + 1480268.

It is an arithmetic number, because the mean of its divisors is an integer number (150953268).

Almost surely, 2^991555445 is an apocalyptic number.

It is an amenable number.

991555445 is a deficient number, since it is larger than the sum of its proper divisors (216070699).

991555445 is a wasteful number, since it uses less digits than its factorization.

991555445 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2959939.

The product of its digits is 810000, while the sum is 47.

The square root of 991555445 is about 31488.9733875209. The cubic root of 991555445 is about 997.1771875609.

The spelling of 991555445 in words is "nine hundred ninety-one million, five hundred fifty-five thousand, four hundred forty-five".