21155015112550 has 48 divisors (see below), whose sum is σ = 43173573022512. Its totient is φ = 7648266070400.

The previous prime is 21155015112529. The next prime is 21155015112559. The reversal of 21155015112550 is 5521151055112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21155015112559) 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 23 ways as a sum of consecutive naturals, for example, 111071509 + ... + 111261808.

It is an arithmetic number, because the mean of its divisors is an integer number (899449437969).

Almost surely, 2^{21155015112550} is an apocalyptic number.

21155015112550 is an abundant number, since it is smaller than the sum of its proper divisors (22018557909962).

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

21155015112550 is a wasteful number, since it uses less digits than its factorization.

21155015112550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 222333513 (or 222333508 counting only the distinct ones).

The product of its (nonzero) digits is 12500, while the sum is 34.

Adding to 21155015112550 its reverse (5521151055112), we get a palindrome (26676166167662).

The spelling of 21155015112550 in words is "twenty-one trillion, one hundred fifty-five billion, fifteen million, one hundred twelve thousand, five hundred fifty".