21171491128 has 8 divisors (see below), whose sum is σ = 39696545880. Its totient is φ = 10585745560.

The previous prime is 21171491119. The next prime is 21171491129. The reversal of 21171491128 is 82119417112.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21171491129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1323218188 + ... + 1323218203.

It is an arithmetic number, because the mean of its divisors is an integer number (4962068235).

Almost surely, 2^21171491128 is an apocalyptic number.

It is an amenable number.

21171491128 is a deficient number, since it is larger than the sum of its proper divisors (18525054752).

21171491128 is a wasteful number, since it uses less digits than its factorization.

21171491128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2646436397 (or 2646436393 counting only the distinct ones).

The product of its digits is 8064, while the sum is 37.

The spelling of 21171491128 in words is "twenty-one billion, one hundred seventy-one million, four hundred ninety-one thousand, one hundred twenty-eight".