21044389 has 2 divisors, whose sum is σ = 21044390. Its totient is φ = 21044388.

The previous prime is 21044383. The next prime is 21044399. The reversal of 21044389 is 98344012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15484225 + 5560164 = 3935^2 + 2358^2 .

It is a cyclic number.

It is not a de Polignac number, because 21044389 - 2¹⁵ = 21011621 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21044389.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21044383) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10522194 + 10522195.

It is an arithmetic number, because the mean of its divisors is an integer number (10522195).

Almost surely, 2^21044389 is an apocalyptic number.

It is an amenable number.

21044389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21044389 is an equidigital number, since it uses as much as digits as its factorization.

21044389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21044389 is about 4587.4163752596. The cubic root of 21044389 is about 276.0866711279.

The spelling of 21044389 in words is "twenty-one million, forty-four thousand, three hundred eighty-nine".