21389087 has 2 divisors, whose sum is σ = 21389088. Its totient is φ = 21389086.

The previous prime is 21389063. The next prime is 21389107. The reversal of 21389087 is 78098312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21389087 - 2⁸ = 21388831 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21389087.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21389887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10694543 + 10694544.

It is an arithmetic number, because the mean of its divisors is an integer number (10694544).

Almost surely, 2^21389087 is an apocalyptic number.

21389087 is a deficient number, since it is larger than the sum of its proper divisors (1).

21389087 is an equidigital number, since it uses as much as digits as its factorization.

21389087 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 21389087 is about 4624.8337267409. The cubic root of 21389087 is about 277.5859085260.

The spelling of 21389087 in words is "twenty-one million, three hundred eighty-nine thousand, eighty-seven".