21506418023 has 2 divisors, whose sum is σ = 21506418024. Its totient is φ = 21506418022.

The previous prime is 21506418013. The next prime is 21506418049. The reversal of 21506418023 is 32081460512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21506418023 - 2⁴ = 21506418007 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506418013) 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, 10753209011 + 10753209012.

It is an arithmetic number, because the mean of its divisors is an integer number (10753209012).

Almost surely, 2^21506418023 is an apocalyptic number.

21506418023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506418023 is an equidigital number, since it uses as much as digits as its factorization.

21506418023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 32.

Adding to 21506418023 its reverse (32081460512), we get a palindrome (53587878535).

The spelling of 21506418023 in words is "twenty-one billion, five hundred six million, four hundred eighteen thousand, twenty-three".