19910991910 has 16 divisors (see below), whose sum is σ = 35842712400. Its totient is φ = 7963746336.

The previous prime is 19910991871. The next prime is 19910991943. The reversal of 19910991910 is 1919901991.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58756 + ... + 208024.

It is an arithmetic number, because the mean of its divisors is an integer number (2240169525).

Almost surely, 2^19910991910 is an apocalyptic number.

19910991910 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

19910991910 is a deficient number, since it is larger than the sum of its proper divisors (15931720490).

19910991910 is a wasteful number, since it uses less digits than its factorization.

19910991910 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 162615.

The product of its (nonzero) digits is 59049, while the sum is 49.

The spelling of 19910991910 in words is "nineteen billion, nine hundred ten million, nine hundred ninety-one thousand, nine hundred ten".