21701389 has 2 divisors, whose sum is σ = 21701390. Its totient is φ = 21701388.

The previous prime is 21701377. The next prime is 21701413. The reversal of 21701389 is 98310712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18922500 + 2778889 = 4350^2 + 1667^2 .

It is a cyclic number.

It is not a de Polignac number, because 21701389 - 2⁷ = 21701261 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21701389.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21701089) 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, 10850694 + 10850695.

It is an arithmetic number, because the mean of its divisors is an integer number (10850695).

Almost surely, 2^21701389 is an apocalyptic number.

It is an amenable number.

21701389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21701389 is an equidigital number, since it uses as much as digits as its factorization.

21701389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21701389 is about 4658.4749650503. The cubic root of 21701389 is about 278.9303963436.

The spelling of 21701389 in words is "twenty-one million, seven hundred one thousand, three hundred eighty-nine".