21535507055 has 4 divisors (see below), whose sum is σ = 25842608472. Its totient is φ = 17228405640.

The previous prime is 21535507051. The next prime is 21535507067. The reversal of 21535507055 is 55070553512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21535507055 - 2² = 21535507051 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 (21535507051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2153550701 + ... + 2153550710.

It is an arithmetic number, because the mean of its divisors is an integer number (6460652118).

Almost surely, 2^21535507055 is an apocalyptic number.

21535507055 is a deficient number, since it is larger than the sum of its proper divisors (4307101417).

21535507055 is an equidigital number, since it uses as much as digits as its factorization.

21535507055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4307101416.

The product of its (nonzero) digits is 131250, while the sum is 38.

The spelling of 21535507055 in words is "twenty-one billion, five hundred thirty-five million, five hundred seven thousand, fifty-five".