91000000990 has 16 divisors (see below), whose sum is σ = 166244779152. Its totient is φ = 35856716544.

The previous prime is 91000000981. The next prime is 91000000991. The reversal of 91000000990 is 9900000019.

91000000990 is a modest number, since divided by 990 gives 910 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91000000991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 67909779 + ... + 67911118.

It is an arithmetic number, because the mean of its divisors is an integer number (10390298697).

Almost surely, 2^91000000990 is an apocalyptic number.

91000000990 is a deficient number, since it is larger than the sum of its proper divisors (75244778162).

91000000990 is a wasteful number, since it uses less digits than its factorization.

91000000990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 135820971.

The product of its (nonzero) digits is 729, while the sum is 28.

The spelling of 91000000990 in words is "ninety-one billion, nine hundred ninety", and thus it is an aban number.