21500242147 has 2 divisors, whose sum is σ = 21500242148. Its totient is φ = 21500242146.

The previous prime is 21500242117. The next prime is 21500242163. The reversal of 21500242147 is 74124200512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21500242147 - 2⁷ = 21500242019 is a prime.

It is not a weakly prime, because it can be changed into another prime (21500242117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10750121073 + 10750121074.

It is an arithmetic number, because the mean of its divisors is an integer number (10750121074).

Almost surely, 2^21500242147 is an apocalyptic number.

21500242147 is a deficient number, since it is larger than the sum of its proper divisors (1).

21500242147 is an equidigital number, since it uses as much as digits as its factorization.

21500242147 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4480, while the sum is 28.

Adding to 21500242147 its reverse (74124200512), we get a palindrome (95624442659).

The spelling of 21500242147 in words is "twenty-one billion, five hundred million, two hundred forty-two thousand, one hundred forty-seven".