21015222541 has 2 divisors, whose sum is σ = 21015222542. Its totient is φ = 21015222540.

The previous prime is 21015222533. The next prime is 21015222577. The reversal of 21015222541 is 14522251012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14526275625 + 6488946916 = 120525^2 + 80554^2 .

It is a cyclic number.

It is not a de Polignac number, because 21015222541 - 2³ = 21015222533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21015222341) by changing a digit.

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 as a sum of consecutive naturals, namely, 10507611270 + 10507611271.

It is an arithmetic number, because the mean of its divisors is an integer number (10507611271).

Almost surely, 2^21015222541 is an apocalyptic number.

It is an amenable number.

21015222541 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015222541 is an equidigital number, since it uses as much as digits as its factorization.

21015222541 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 21015222541 its reverse (14522251012), we get a palindrome (35537473553).

The spelling of 21015222541 in words is "twenty-one billion, fifteen million, two hundred twenty-two thousand, five hundred forty-one".