21256764127 has 2 divisors, whose sum is σ = 21256764128. Its totient is φ = 21256764126.

The previous prime is 21256764107. The next prime is 21256764157. The reversal of 21256764127 is 72146765212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21256764127 - 2⁷ = 21256763999 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21256764107) 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, 10628382063 + 10628382064.

It is an arithmetic number, because the mean of its divisors is an integer number (10628382064).

Almost surely, 2^21256764127 is an apocalyptic number.

21256764127 is a deficient number, since it is larger than the sum of its proper divisors (1).

21256764127 is an equidigital number, since it uses as much as digits as its factorization.

21256764127 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 282240, while the sum is 43.

The spelling of 21256764127 in words is "twenty-one billion, two hundred fifty-six million, seven hundred sixty-four thousand, one hundred twenty-seven".