21705385575 has 24 divisors (see below), whose sum is σ = 35979982848. Its totient is φ = 11545965280.

The previous prime is 21705385571. The next prime is 21705385589. The reversal of 21705385575 is 57558350712.

It is not a de Polignac number, because 21705385575 - 2² = 21705385571 is a prime.

It is a super-2 number, since 2×21705385575² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21705385571) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 349089 + ... + 406538.

It is an arithmetic number, because the mean of its divisors is an integer number (1499165952).

Almost surely, 2^21705385575 is an apocalyptic number.

21705385575 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21705385575 is a deficient number, since it is larger than the sum of its proper divisors (14274597273).

21705385575 is a wasteful number, since it uses less digits than its factorization.

21705385575 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 756023 (or 756018 counting only the distinct ones).

The product of its (nonzero) digits is 1470000, while the sum is 48.

The spelling of 21705385575 in words is "twenty-one billion, seven hundred five million, three hundred eighty-five thousand, five hundred seventy-five".