21785405761 has 8 divisors (see below), whose sum is σ = 25130295360. Its totient is φ = 18498688368.

The previous prime is 21785405743. The next prime is 21785405783. The reversal of 21785405761 is 16750458712.

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 21785405761 - 2⁹ = 21785405249 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21785405731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14542246 + ... + 14543743.

It is an arithmetic number, because the mean of its divisors is an integer number (3141286920).

Almost surely, 2^21785405761 is an apocalyptic number.

It is an amenable number.

21785405761 is a deficient number, since it is larger than the sum of its proper divisors (3344889599).

21785405761 is a wasteful number, since it uses less digits than its factorization.

21785405761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29086103.

The product of its (nonzero) digits is 470400, while the sum is 46.

The spelling of 21785405761 in words is "twenty-one billion, seven hundred eighty-five million, four hundred five thousand, seven hundred sixty-one".