21521352247 has 2 divisors, whose sum is σ = 21521352248. Its totient is φ = 21521352246.

The previous prime is 21521352211. The next prime is 21521352277. The reversal of 21521352247 is 74225312512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21521352247 - 2¹¹ = 21521350199 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21521352277) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10760676123 + 10760676124.

It is an arithmetic number, because the mean of its divisors is an integer number (10760676124).

Almost surely, 2^21521352247 is an apocalyptic number.

21521352247 is a deficient number, since it is larger than the sum of its proper divisors (1).

21521352247 is an equidigital number, since it uses as much as digits as its factorization.

21521352247 is an evil number, because the sum of its binary digits is even.

The product of its digits is 33600, while the sum is 34.

Adding to 21521352247 its reverse (74225312512), we get a palindrome (95746664759).

The spelling of 21521352247 in words is "twenty-one billion, five hundred twenty-one million, three hundred fifty-two thousand, two hundred forty-seven".