991955555 has 8 divisors (see below), whose sum is σ = 1207112544. Its totient is φ = 782387200.

The previous prime is 991955537. The next prime is 991955557. The reversal of 991955555 is 555559199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 991955555 - 2¹² = 991951459 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 991955497 and 991955506.

It is not an unprimeable number, because it can be changed into a prime (991955557) 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, 1396766 + ... + 1397475.

It is an arithmetic number, because the mean of its divisors is an integer number (150889068).

Almost surely, 2^991955555 is an apocalyptic number.

991955555 is a deficient number, since it is larger than the sum of its proper divisors (215156989).

991955555 is a wasteful number, since it uses less digits than its factorization.

991955555 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2794317.

The product of its digits is 2278125, while the sum is 53.

The square root of 991955555 is about 31495.3259230636. The cubic root of 991955555 is about 997.3112956814.

The spelling of 991955555 in words is "nine hundred ninety-one million, nine hundred fifty-five thousand, five hundred fifty-five".