21135889 has 2 divisors, whose sum is σ = 21135890. Its totient is φ = 21135888.

The previous prime is 21135857. The next prime is 21135901. The reversal of 21135889 is 98853112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20657025 + 478864 = 4545^2 + 692^2 .

It is a cyclic number.

It is not a de Polignac number, because 21135889 - 2⁵ = 21135857 is a prime.

It is not a weakly prime, because it can be changed into another prime (21135839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10567944 + 10567945.

It is an arithmetic number, because the mean of its divisors is an integer number (10567945).

Almost surely, 2^21135889 is an apocalyptic number.

It is an amenable number.

21135889 is a deficient number, since it is larger than the sum of its proper divisors (1).

21135889 is an equidigital number, since it uses as much as digits as its factorization.

21135889 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 37.

The square root of 21135889 is about 4597.3784921409. The cubic root of 21135889 is about 276.4862298263.

It can be divided in two parts, 211 and 35889, that added together give a square (36100 = 190²).

The spelling of 21135889 in words is "twenty-one million, one hundred thirty-five thousand, eight hundred eighty-nine".