21055540655 has 8 divisors (see below), whose sum is σ = 26752922352. Its totient is φ = 15853583488.

The previous prime is 21055540651. The next prime is 21055540657. The reversal of 21055540655 is 55604555012.

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 21055540655 - 2² = 21055540651 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 (21055540651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 123856037 + ... + 123856206.

It is an arithmetic number, because the mean of its divisors is an integer number (3344115294).

Almost surely, 2^21055540655 is an apocalyptic number.

21055540655 is a deficient number, since it is larger than the sum of its proper divisors (5697381697).

21055540655 is a wasteful number, since it uses less digits than its factorization.

21055540655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247712265.

The product of its (nonzero) digits is 150000, while the sum is 38.

The spelling of 21055540655 in words is "twenty-one billion, fifty-five million, five hundred forty thousand, six hundred fifty-five".