21506740301531 has 2 divisors, whose sum is σ = 21506740301532. Its totient is φ = 21506740301530.

The previous prime is 21506740301513. The next prime is 21506740301567. The reversal of 21506740301531 is 13510304760512.

It is a happy number.

Together with previous prime (21506740301513) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21506740301531 is a prime.

It is a super-2 number, since 2×21506740301531² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21506740321531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10753370150765 + 10753370150766.

It is an arithmetic number, because the mean of its divisors is an integer number (10753370150766).

Almost surely, 2^{21506740301531} is an apocalyptic number.

21506740301531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506740301531 is an equidigital number, since it uses as much as digits as its factorization.

21506740301531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 75600, while the sum is 38.

The spelling of 21506740301531 in words is "twenty-one trillion, five hundred six billion, seven hundred forty million, three hundred one thousand, five hundred thirty-one".