21013250550 has 24 divisors (see below), whose sum is σ = 52112861736. Its totient is φ = 5603533440.

The previous prime is 21013250543. The next prime is 21013250579. The reversal of 21013250550 is 5505231012.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21013250550.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70044019 + ... + 70044318.

It is an arithmetic number, because the mean of its divisors is an integer number (2171369239).

Almost surely, 2^21013250550 is an apocalyptic number.

21013250550 is an abundant number, since it is smaller than the sum of its proper divisors (31099611186).

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

21013250550 is a wasteful number, since it uses less digits than its factorization.

21013250550 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140088352 (or 140088347 counting only the distinct ones).

The product of its (nonzero) digits is 1500, while the sum is 24.

Adding to 21013250550 its reverse (5505231012), we get a palindrome (26518481562).

The spelling of 21013250550 in words is "twenty-one billion, thirteen million, two hundred fifty thousand, five hundred fifty".