21866329 has 2 divisors, whose sum is σ = 21866330. Its totient is φ = 21866328.

The previous prime is 21866311. The next prime is 21866333. The reversal of 21866329 is 92366812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19758025 + 2108304 = 4445^2 + 1452^2 .

It is a cyclic number.

It is not a de Polignac number, because 21866329 - 2¹¹ = 21864281 is a prime.

It is not a weakly prime, because it can be changed into another prime (21866729) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10933164 + 10933165.

It is an arithmetic number, because the mean of its divisors is an integer number (10933165).

Almost surely, 2^21866329 is an apocalyptic number.

It is an amenable number.

21866329 is a deficient number, since it is larger than the sum of its proper divisors (1).

21866329 is an equidigital number, since it uses as much as digits as its factorization.

21866329 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 37.

The square root of 21866329 is about 4676.1446726978. The cubic root of 21866329 is about 279.6352776774.

It can be divided in two parts, 2186 and 6329, that added together give a triangular number (8515 = T₁₃₀).

The spelling of 21866329 in words is "twenty-one million, eight hundred sixty-six thousand, three hundred twenty-nine".