1991023062855 has 16 divisors (see below), whose sum is σ = 3185654836320. Its totient is φ = 1061872988288.

The previous prime is 1991023062851. The next prime is 1991023062913. The reversal of 1991023062855 is 5582603201991.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 1991023062855 - 2² = 1991023062851 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1991023062798 and 1991023062807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991023062851) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4131709 + ... + 4588361.

It is an arithmetic number, because the mean of its divisors is an integer number (199103427270).

Almost surely, 2^{1991023062855} is an apocalyptic number.

1991023062855 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1991023062855 is a deficient number, since it is larger than the sum of its proper divisors (1194631773465).

1991023062855 is a wasteful number, since it uses less digits than its factorization.

1991023062855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 747330.

The product of its (nonzero) digits is 1166400, while the sum is 51.

The spelling of 1991023062855 in words is "one trillion, nine hundred ninety-one billion, twenty-three million, sixty-two thousand, eight hundred fifty-five".