21355030655 has 16 divisors (see below), whose sum is σ = 29380482624. Its totient is φ = 14596657920.

The previous prime is 21355030637. The next prime is 21355030657. The reversal of 21355030655 is 55603055312.

It is not a de Polignac number, because 21355030655 - 2¹² = 21355026559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21355030657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 963716 + ... + 985625.

It is an arithmetic number, because the mean of its divisors is an integer number (1836280164).

Almost surely, 2^21355030655 is an apocalyptic number.

21355030655 is a deficient number, since it is larger than the sum of its proper divisors (8025451969).

21355030655 is a wasteful number, since it uses less digits than its factorization.

21355030655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1949666.

The product of its (nonzero) digits is 67500, while the sum is 35.

Adding to 21355030655 its reverse (55603055312), we get a palindrome (76958085967).

The spelling of 21355030655 in words is "twenty-one billion, three hundred fifty-five million, thirty thousand, six hundred fifty-five".