21310389 has 12 divisors (see below), whose sum is σ = 31843500. Its totient is φ = 13716864.

The previous prime is 21310337. The next prime is 21310417. The reversal of 21310389 is 98301312.

It can be written as a sum of positive squares in 2 ways, for example, as 14884164 + 6426225 = 3858^2 + 2535^2 .

It is not a de Polignac number, because 21310389 - 2⁹ = 21309877 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21310309) 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 in 11 ways as a sum of consecutive naturals, for example, 40564 + ... + 41085.

It is an arithmetic number, because the mean of its divisors is an integer number (2653625).

Almost surely, 2^21310389 is an apocalyptic number.

21310389 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21310389 is a deficient number, since it is larger than the sum of its proper divisors (10533111).

21310389 is a wasteful number, since it uses less digits than its factorization.

21310389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81684 (or 81681 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 27.

The square root of 21310389 is about 4616.3176883746. The cubic root of 21310389 is about 277.2450446217.

The spelling of 21310389 in words is "twenty-one million, three hundred ten thousand, three hundred eighty-nine".