21186793 has 2 divisors, whose sum is σ = 21186794. Its totient is φ = 21186792.

The previous prime is 21186769. The next prime is 21186799. The reversal of 21186793 is 39768112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12938409 + 8248384 = 3597^2 + 2872^2 .

It is a cyclic number.

It is not a de Polignac number, because 21186793 - 2⁹ = 21186281 is a prime.

It is not a weakly prime, because it can be changed into another prime (21186799) 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, 10593396 + 10593397.

It is an arithmetic number, because the mean of its divisors is an integer number (10593397).

Almost surely, 2^21186793 is an apocalyptic number.

It is an amenable number.

21186793 is a deficient number, since it is larger than the sum of its proper divisors (1).

21186793 is an equidigital number, since it uses as much as digits as its factorization.

21186793 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 21186793 is about 4602.9113613017. The cubic root of 21186793 is about 276.7080164322.

It can be divided in two parts, 2118 and 6793, that added together give a triangular number (8911 = T₁₃₃).

The spelling of 21186793 in words is "twenty-one million, one hundred eighty-six thousand, seven hundred ninety-three".