21506206001543 has 2 divisors, whose sum is σ = 21506206001544. Its totient is φ = 21506206001542.

The previous prime is 21506206001507. The next prime is 21506206001591. The reversal of 21506206001543 is 34510060260512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21506206001543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21506206001593) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753103000771 + 10753103000772.

It is an arithmetic number, because the mean of its divisors is an integer number (10753103000772).

Almost surely, 2^{21506206001543} is an apocalyptic number.

21506206001543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506206001543 is an equidigital number, since it uses as much as digits as its factorization.

21506206001543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21506206001543 in words is "twenty-one trillion, five hundred six billion, two hundred six million, one thousand, five hundred forty-three".