21209937609577 has 2 divisors, whose sum is σ = 21209937609578. Its totient is φ = 21209937609576.

The previous prime is 21209937609569. The next prime is 21209937609607. The reversal of 21209937609577 is 77590673990212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18127932651481 + 3082004958096 = 4257691^2 + 1755564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21209937609577 - 2³ = 21209937609569 is a prime.

It is a super-2 number, since 2×21209937609577² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21209937639577) 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, 10604968804788 + 10604968804789.

It is an arithmetic number, because the mean of its divisors is an integer number (10604968804789).

Almost surely, 2^{21209937609577} is an apocalyptic number.

It is an amenable number.

21209937609577 is a deficient number, since it is larger than the sum of its proper divisors (1).

21209937609577 is an equidigital number, since it uses as much as digits as its factorization.

21209937609577 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 90016920, while the sum is 67.

The spelling of 21209937609577 in words is "twenty-one trillion, two hundred nine billion, nine hundred thirty-seven million, six hundred nine thousand, five hundred seventy-seven".