21767827 has 2 divisors, whose sum is σ = 21767828. Its totient is φ = 21767826.

The previous prime is 21767813. The next prime is 21767839. The reversal of 21767827 is 72876712.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21767827 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21767827.

It is not a weakly prime, because it can be changed into another prime (21767807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10883913 + 10883914.

It is an arithmetic number, because the mean of its divisors is an integer number (10883914).

Almost surely, 2^21767827 is an apocalyptic number.

21767827 is a deficient number, since it is larger than the sum of its proper divisors (1).

21767827 is an equidigital number, since it uses as much as digits as its factorization.

21767827 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 65856, while the sum is 40.

The square root of 21767827 is about 4665.6003900891. The cubic root of 21767827 is about 279.2147513915.

It can be divided in two parts, 217678 and 27, that multiplied together give a triangular number (5877306 = T₃₄₂₈).

The spelling of 21767827 in words is "twenty-one million, seven hundred sixty-seven thousand, eight hundred twenty-seven".