21655505667 has 8 divisors (see below), whose sum is σ = 28878036160. Its totient is φ = 14434989480.

The previous prime is 21655505639. The next prime is 21655505689. The reversal of 21655505667 is 76650555612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21655505667 - 2¹¹ = 21655503619 is a prime.

It is a super-2 number, since 2×21655505667² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21655505467) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 478309 + ... + 521622.

It is an arithmetic number, because the mean of its divisors is an integer number (3609754520).

Almost surely, 2^21655505667 is an apocalyptic number.

21655505667 is a deficient number, since it is larger than the sum of its proper divisors (7222530493).

21655505667 is an equidigital number, since it uses as much as digits as its factorization.

21655505667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1007153.

The product of its (nonzero) digits is 1890000, while the sum is 48.

The spelling of 21655505667 in words is "twenty-one billion, six hundred fifty-five million, five hundred five thousand, six hundred sixty-seven".