21138055224 has 128 divisors (see below), whose sum is σ = 64224921600. Its totient is φ = 5708828160.

The previous prime is 21138055207. The next prime is 21138055249. The reversal of 21138055224 is 42255083112.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6664 + ... + 205719.

It is an arithmetic number, because the mean of its divisors is an integer number (501757200).

Almost surely, 2^21138055224 is an apocalyptic number.

21138055224 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21138055224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32112460800).

21138055224 is an abundant number, since it is smaller than the sum of its proper divisors (43086866376).

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

21138055224 is a wasteful number, since it uses less digits than its factorization.

21138055224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212445 (or 212441 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 33.

The spelling of 21138055224 in words is "twenty-one billion, one hundred thirty-eight million, fifty-five thousand, two hundred twenty-four".