21645396655 has 8 divisors (see below), whose sum is σ = 25975272672. Its totient is φ = 17315786208.

The previous prime is 21645396649. The next prime is 21645396667. The reversal of 21645396655 is 55669354612.

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 21645396655 - 2²³ = 21637008047 is a prime.

It is a super-3 number, since 3×21645396655³ (a number of 32 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 250009 + ... + 325261.

It is an arithmetic number, because the mean of its divisors is an integer number (3246909084).

Almost surely, 2^21645396655 is an apocalyptic number.

21645396655 is a deficient number, since it is larger than the sum of its proper divisors (4329876017).

21645396655 is an equidigital number, since it uses as much as digits as its factorization.

21645396655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132785.

The product of its digits is 5832000, while the sum is 52.

The spelling of 21645396655 in words is "twenty-one billion, six hundred forty-five million, three hundred ninety-six thousand, six hundred fifty-five".