21356666503 has 2 divisors, whose sum is σ = 21356666504. Its totient is φ = 21356666502.

The previous prime is 21356666497. The next prime is 21356666521. The reversal of 21356666503 is 30566665312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21356666503 - 2²⁵ = 21323112071 is a prime.

It is a super-2 number, since 2×21356666503² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21356666503.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21356666543) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678333251 + 10678333252.

It is an arithmetic number, because the mean of its divisors is an integer number (10678333252).

Almost surely, 2^21356666503 is an apocalyptic number.

21356666503 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356666503 is an equidigital number, since it uses as much as digits as its factorization.

21356666503 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 583200, while the sum is 43.

The spelling of 21356666503 in words is "twenty-one billion, three hundred fifty-six million, six hundred sixty-six thousand, five hundred three".