21375172117577 has 2 divisors, whose sum is σ = 21375172117578. Its totient is φ = 21375172117576.

The previous prime is 21375172117571. The next prime is 21375172117627. The reversal of 21375172117577 is 77571127157312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12263835904576 + 9111336213001 = 3501976^2 + 3018499^2 .

It is a cyclic number.

It is not a de Polignac number, because 21375172117577 - 2⁶ = 21375172117513 is a prime.

It is not a weakly prime, because it can be changed into another prime (21375172117571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10687586058788 + 10687586058789.

It is an arithmetic number, because the mean of its divisors is an integer number (10687586058789).

Almost surely, 2^{21375172117577} is an apocalyptic number.

It is an amenable number.

21375172117577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21375172117577 is an equidigital number, since it uses as much as digits as its factorization.

21375172117577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5042100, while the sum is 56.

The spelling of 21375172117577 in words is "twenty-one trillion, three hundred seventy-five billion, one hundred seventy-two million, one hundred seventeen thousand, five hundred seventy-seven".