21416389 has 2 divisors, whose sum is σ = 21416390. Its totient is φ = 21416388.

The previous prime is 21416387. The next prime is 21416411. The reversal of 21416389 is 98361412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17181025 + 4235364 = 4145^2 + 2058^2 .

It is a cyclic number.

It is not a de Polignac number, because 21416389 - 2¹ = 21416387 is a prime.

It is a super-3 number, since 3×21416389³ (a number of 23 digits) contains 333 as substring.

Together with 21416387, it forms a pair of twin primes.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21416383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10708194 + 10708195.

It is an arithmetic number, because the mean of its divisors is an integer number (10708195).

Almost surely, 2^21416389 is an apocalyptic number.

It is an amenable number.

21416389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21416389 is an equidigital number, since it uses as much as digits as its factorization.

21416389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 34.

The square root of 21416389 is about 4627.7844591122. The cubic root of 21416389 is about 277.7039660535.

The spelling of 21416389 in words is "twenty-one million, four hundred sixteen thousand, three hundred eighty-nine".