21727377509 has 2 divisors, whose sum is σ = 21727377510. Its totient is φ = 21727377508.

The previous prime is 21727377461. The next prime is 21727377541. The reversal of 21727377509 is 90577372712.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18602232100 + 3125145409 = 136390^2 + 55903^2 .

It is a cyclic number.

It is not a de Polignac number, because 21727377509 - 2¹⁶ = 21727311973 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21727377809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10863688754 + 10863688755.

It is an arithmetic number, because the mean of its divisors is an integer number (10863688755).

Almost surely, 2^21727377509 is an apocalyptic number.

It is an amenable number.

21727377509 is a deficient number, since it is larger than the sum of its proper divisors (1).

21727377509 is an equidigital number, since it uses as much as digits as its factorization.

21727377509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296540, while the sum is 50.

The spelling of 21727377509 in words is "twenty-one billion, seven hundred twenty-seven million, three hundred seventy-seven thousand, five hundred nine".