21221535353550 has 48 divisors (see below), whose sum is σ = 60147894490752. Its totient is φ = 4850636652000.

The previous prime is 21221535353509. The next prime is 21221535353597. The reversal of 21221535353550 is 5535353512212.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10105491976 + ... + 10105494075.

It is an arithmetic number, because the mean of its divisors is an integer number (1253081135224).

Almost surely, 2^{21221535353550} is an apocalyptic number.

21221535353550 is an abundant number, since it is smaller than the sum of its proper divisors (38926359137202).

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

21221535353550 is a wasteful number, since it uses less digits than its factorization.

21221535353550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20210986073 (or 20210986068 counting only the distinct ones).

The product of its (nonzero) digits is 675000, while the sum is 42.

Adding to 21221535353550 its reverse (5535353512212), we get a palindrome (26756888865762).

The spelling of 21221535353550 in words is "twenty-one trillion, two hundred twenty-one billion, five hundred thirty-five million, three hundred fifty-three thousand, five hundred fifty".