21140389 has 2 divisors, whose sum is σ = 21140390. Its totient is φ = 21140388.

The previous prime is 21140377. The next prime is 21140423. The reversal of 21140389 is 98304112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20930625 + 209764 = 4575^2 + 458^2 .

It is a cyclic number.

It is not a de Polignac number, because 21140389 - 2¹³ = 21132197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21140089) 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, 10570194 + 10570195.

It is an arithmetic number, because the mean of its divisors is an integer number (10570195).

Almost surely, 2^21140389 is an apocalyptic number.

It is an amenable number.

21140389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21140389 is an equidigital number, since it uses as much as digits as its factorization.

21140389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21140389 is about 4597.8678754397. The cubic root of 21140389 is about 276.5058504779.

The spelling of 21140389 in words is "twenty-one million, one hundred forty thousand, three hundred eighty-nine".