21506323427 has 2 divisors, whose sum is σ = 21506323428. Its totient is φ = 21506323426.

The previous prime is 21506323357. The next prime is 21506323441. The reversal of 21506323427 is 72432360512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21506323427 - 2¹⁰ = 21506322403 is a prime.

It is not a weakly prime, because it can be changed into another prime (21506323477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753161713 + 10753161714.

It is an arithmetic number, because the mean of its divisors is an integer number (10753161714).

Almost surely, 2^21506323427 is an apocalyptic number.

21506323427 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506323427 is an equidigital number, since it uses as much as digits as its factorization.

21506323427 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 60480, while the sum is 35.

Adding to 21506323427 its reverse (72432360512), we get a palindrome (93938683939).

The spelling of 21506323427 in words is "twenty-one billion, five hundred six million, three hundred twenty-three thousand, four hundred twenty-seven".