21546109791 has 12 divisors (see below), whose sum is σ = 32952874032. Its totient is φ = 13519127616.

The previous prime is 21546109777. The next prime is 21546109799. The reversal of 21546109791 is 19790164512.

21546109791 is a `hidden beast` number, since 2 + 1 + 546 + 10 + 9 + 7 + 91 = 666.

It is not a de Polignac number, because 21546109791 - 2⁶ = 21546109727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21546109799) 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 in 11 ways as a sum of consecutive naturals, for example, 70411971 + ... + 70412276.

It is an arithmetic number, because the mean of its divisors is an integer number (2746072836).

Almost surely, 2^21546109791 is an apocalyptic number.

21546109791 is a deficient number, since it is larger than the sum of its proper divisors (11406764241).

21546109791 is a wasteful number, since it uses less digits than its factorization.

21546109791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140824270 (or 140824267 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The spelling of 21546109791 in words is "twenty-one billion, five hundred forty-six million, one hundred nine thousand, seven hundred ninety-one".