21001192091 has 12 divisors (see below), whose sum is σ = 23094378552. Its totient is φ = 19083372000.

The previous prime is 21001192067. The next prime is 21001192117. The reversal of 21001192091 is 19029110012.

It is not a de Polignac number, because 21001192091 - 2¹⁰ = 21001191067 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21001192091.

It is not an unprimeable number, because it can be changed into a prime (21001192001) 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 11 ways as a sum of consecutive naturals, for example, 237956 + ... + 314046.

It is an arithmetic number, because the mean of its divisors is an integer number (1924531546).

Almost surely, 2^21001192091 is an apocalyptic number.

21001192091 is a deficient number, since it is larger than the sum of its proper divisors (2093186461).

21001192091 is a wasteful number, since it uses less digits than its factorization.

21001192091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 78394 (or 78383 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 26.

The spelling of 21001192091 in words is "twenty-one billion, one million, one hundred ninety-two thousand, ninety-one".