21868039 has 2 divisors, whose sum is σ = 21868040. Its totient is φ = 21868038.

The previous prime is 21868013. The next prime is 21868043. The reversal of 21868039 is 93086812.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21868039 is a prime.

It is a super-2 number, since 2×21868039² = 956422259411042, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21867989 and 21868007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21868139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10934019 + 10934020.

It is an arithmetic number, because the mean of its divisors is an integer number (10934020).

Almost surely, 2^21868039 is an apocalyptic number.

21868039 is a deficient number, since it is larger than the sum of its proper divisors (1).

21868039 is an equidigital number, since it uses as much as digits as its factorization.

21868039 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 21868039 is about 4676.3275120547. The cubic root of 21868039 is about 279.6425668732.

It can be divided in two parts, 2186803 and 9, that added together give a palindrome (2186812).

The spelling of 21868039 in words is "twenty-one million, eight hundred sixty-eight thousand, thirty-nine".