21375567377 has 2 divisors, whose sum is σ = 21375567378. Its totient is φ = 21375567376.

The previous prime is 21375567349. The next prime is 21375567391. The reversal of 21375567377 is 77376557312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11150515216 + 10225052161 = 105596^2 + 101119^2 .

It is a cyclic number.

It is not a de Polignac number, because 21375567377 - 2²⁰ = 21374518801 is a prime.

It is not a weakly prime, because it can be changed into another prime (21375567077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10687783688 + 10687783689.

It is an arithmetic number, because the mean of its divisors is an integer number (10687783689).

Almost surely, 2^21375567377 is an apocalyptic number.

It is an amenable number.

21375567377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21375567377 is an equidigital number, since it uses as much as digits as its factorization.

21375567377 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6482700, while the sum is 53.

The spelling of 21375567377 in words is "twenty-one billion, three hundred seventy-five million, five hundred sixty-seven thousand, three hundred seventy-seven".