21491109512 has 16 divisors (see below), whose sum is σ = 40341790860. Its totient is φ = 10733298624.

The previous prime is 21491109511. The next prime is 21491109527. The reversal of 21491109512 is 21590119412.

It can be written as a sum of positive squares in 2 ways, for example, as 16329261796 + 5161847716 = 127786^2 + 71846^2 .

It is not an unprimeable number, because it can be changed into a prime (21491109511) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1524563 + ... + 1538594.

Almost surely, 2^21491109512 is an apocalyptic number.

It is an amenable number.

21491109512 is a deficient number, since it is larger than the sum of its proper divisors (18850681348).

21491109512 is a wasteful number, since it uses less digits than its factorization.

21491109512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3064040 (or 3064036 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 35.

The spelling of 21491109512 in words is "twenty-one billion, four hundred ninety-one million, one hundred nine thousand, five hundred twelve".