21277619809 has 2 divisors, whose sum is σ = 21277619810. Its totient is φ = 21277619808.

The previous prime is 21277619807. The next prime is 21277619863. The reversal of 21277619809 is 90891677212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18795587409 + 2482032400 = 137097^2 + 49820^2 .

It is a cyclic number.

It is not a de Polignac number, because 21277619809 - 2¹ = 21277619807 is a prime.

Together with 21277619807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21277619801) 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, 10638809904 + 10638809905.

It is an arithmetic number, because the mean of its divisors is an integer number (10638809905).

Almost surely, 2^21277619809 is an apocalyptic number.

It is an amenable number.

21277619809 is a deficient number, since it is larger than the sum of its proper divisors (1).

21277619809 is an equidigital number, since it uses as much as digits as its factorization.

21277619809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 762048, while the sum is 52.

The spelling of 21277619809 in words is "twenty-one billion, two hundred seventy-seven million, six hundred nineteen thousand, eight hundred nine".