21205222255 has 64 divisors (see below), whose sum is σ = 33000099840. Its totient is φ = 12736272384.

The previous prime is 21205222253. The next prime is 21205222267. The reversal of 21205222255 is 55222250212.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21205222255 - 2¹ = 21205222253 is a prime.

It is a super-2 number, since 2×21205222255² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21205222253) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 485406 + ... + 527284.

It is an arithmetic number, because the mean of its divisors is an integer number (515626560).

Almost surely, 2^21205222255 is an apocalyptic number.

21205222255 is a deficient number, since it is larger than the sum of its proper divisors (11794877585).

21205222255 is a wasteful number, since it uses less digits than its factorization.

21205222255 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41968.

The product of its (nonzero) digits is 8000, while the sum is 28.

Adding to 21205222255 its reverse (55222250212), we get a palindrome (76427472467).

The spelling of 21205222255 in words is "twenty-one billion, two hundred five million, two hundred twenty-two thousand, two hundred fifty-five".