21195991873 has 8 divisors (see below), whose sum is σ = 24225203520. Its totient is φ = 18167083440.

The previous prime is 21195991793. The next prime is 21195991889. The reversal of 21195991873 is 37819959112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21195991873 - 2¹⁷ = 21195860801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21195991373) 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, 101718 + ... + 229648.

It is an arithmetic number, because the mean of its divisors is an integer number (3028150440).

Almost surely, 2^21195991873 is an apocalyptic number.

It is an amenable number.

21195991873 is a deficient number, since it is larger than the sum of its proper divisors (3029211647).

21195991873 is a wasteful number, since it uses less digits than its factorization.

21195991873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151607.

The product of its digits is 1224720, while the sum is 55.

The spelling of 21195991873 in words is "twenty-one billion, one hundred ninety-five million, nine hundred ninety-one thousand, eight hundred seventy-three".