21515050142221 has 32 divisors (see below), whose sum is σ = 21972255595488. Its totient is φ = 21062971883520.

The previous prime is 21515050142207. The next prime is 21515050142233. The reversal of 21515050142221 is 12224105051512.

It can be written as a sum of positive squares in 16 ways, for example, as 42817955625 + 21472232186596 = 206925^2 + 4633814^2 .

It is a cyclic number.

It is not a de Polignac number, because 21515050142221 - 2²¹ = 21515048045069 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21515050142021) 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 31 ways as a sum of consecutive naturals, for example, 12678284445 + ... + 12678286141.

It is an arithmetic number, because the mean of its divisors is an integer number (686632987359).

Almost surely, 2^{21515050142221} is an apocalyptic number.

It is an amenable number.

21515050142221 is a deficient number, since it is larger than the sum of its proper divisors (457205453267).

21515050142221 is a wasteful number, since it uses less digits than its factorization.

21515050142221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4081.

The product of its (nonzero) digits is 8000, while the sum is 31.

Adding to 21515050142221 its reverse (12224105051512), we get a palindrome (33739155193733).

The spelling of 21515050142221 in words is "twenty-one trillion, five hundred fifteen billion, fifty million, one hundred forty-two thousand, two hundred twenty-one".