21121321055550 has 48 divisors (see below), whose sum is σ = 52381721306160. Its totient is φ = 5632261411840.

The previous prime is 21121321055537. The next prime is 21121321055551. The reversal of 21121321055550 is 5555012312112.

It is a super-2 number, since 2×21121321055550² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121321055551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8461966 + ... + 10669934.

It is an arithmetic number, because the mean of its divisors is an integer number (1091285860545).

Almost surely, 2^{21121321055550} is an apocalyptic number.

21121321055550 is an abundant number, since it is smaller than the sum of its proper divisors (31260400250610).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21121321055550 is a wasteful number, since it uses less digits than its factorization.

21121321055550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2271757 (or 2271752 counting only the distinct ones).

The product of its (nonzero) digits is 15000, while the sum is 33.

Adding to 21121321055550 its reverse (5555012312112), we get a palindrome (26676333367662).

The spelling of 21121321055550 in words is "twenty-one trillion, one hundred twenty-one billion, three hundred twenty-one million, fifty-five thousand, five hundred fifty".