21390266851 has 2 divisors, whose sum is σ = 21390266852. Its totient is φ = 21390266850.

The previous prime is 21390266839. The next prime is 21390266927. The reversal of 21390266851 is 15866209312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21390266851 - 2¹⁵ = 21390234083 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21390266798 and 21390266807.

It is not a weakly prime, because it can be changed into another prime (21390266351) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10695133425 + 10695133426.

It is an arithmetic number, because the mean of its divisors is an integer number (10695133426).

Almost surely, 2^21390266851 is an apocalyptic number.

21390266851 is a deficient number, since it is larger than the sum of its proper divisors (1).

21390266851 is an equidigital number, since it uses as much as digits as its factorization.

21390266851 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 43.

The spelling of 21390266851 in words is "twenty-one billion, three hundred ninety million, two hundred sixty-six thousand, eight hundred fifty-one".