21611206655 has 8 divisors (see below), whose sum is σ = 25939380384. Its totient is φ = 17285010400.

The previous prime is 21611206637. The next prime is 21611206657. The reversal of 21611206655 is 55660211612.

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

It is not a de Polignac number, because 21611206655 - 2¹⁶ = 21611141119 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21611206657) 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, 470216 + ... + 514125.

It is an arithmetic number, because the mean of its divisors is an integer number (3242422548).

Almost surely, 2^21611206655 is an apocalyptic number.

21611206655 is a deficient number, since it is larger than the sum of its proper divisors (4328173729).

21611206655 is an equidigital number, since it uses as much as digits as its factorization.

21611206655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 988737.

The product of its (nonzero) digits is 21600, while the sum is 35.

The spelling of 21611206655 in words is "twenty-one billion, six hundred eleven million, two hundred six thousand, six hundred fifty-five".