21873639891 has 8 divisors (see below), whose sum is σ = 29173066704. Its totient is φ = 14578319840.

The previous prime is 21873639707. The next prime is 21873639899. The reversal of 21873639891 is 19893637812.

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 21873639891 - 2⁹ = 21873639379 is a prime.

It is a super-2 number, since 2×21873639891² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21873639899) 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, 1014240 + ... + 1035581.

It is an arithmetic number, because the mean of its divisors is an integer number (3646633338).

Almost surely, 2^21873639891 is an apocalyptic number.

21873639891 is a deficient number, since it is larger than the sum of its proper divisors (7299426813).

21873639891 is a wasteful number, since it uses less digits than its factorization.

21873639891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2053381.

The product of its digits is 3919104, while the sum is 57.

The spelling of 21873639891 in words is "twenty-one billion, eight hundred seventy-three million, six hundred thirty-nine thousand, eight hundred ninety-one".