21016215550 has 48 divisors (see below), whose sum is σ = 42827093712. Its totient is φ = 7609414400.

The previous prime is 21016215527. The next prime is 21016215587. The reversal of 21016215550 is 5551261012.

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, 46152 + ... + 210148.

It is an arithmetic number, because the mean of its divisors is an integer number (892231119).

Almost surely, 2^21016215550 is an apocalyptic number.

21016215550 is an abundant number, since it is smaller than the sum of its proper divisors (21810878162).

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

21016215550 is a wasteful number, since it uses less digits than its factorization.

21016215550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164253 (or 164248 counting only the distinct ones).

The product of its (nonzero) digits is 3000, while the sum is 28.

Adding to 21016215550 its reverse (5551261012), we get a palindrome (26567476562).

The spelling of 21016215550 in words is "twenty-one billion, sixteen million, two hundred fifteen thousand, five hundred fifty".