21389807 has 2 divisors, whose sum is σ = 21389808. Its totient is φ = 21389806.

The previous prime is 21389789. The next prime is 21389827. The reversal of 21389807 is 70898312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21389807 - 2⁶ = 21389743 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21389827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10694903 + 10694904.

It is an arithmetic number, because the mean of its divisors is an integer number (10694904).

Almost surely, 2^21389807 is an apocalyptic number.

21389807 is a deficient number, since it is larger than the sum of its proper divisors (1).

21389807 is an equidigital number, since it uses as much as digits as its factorization.

21389807 is an evil number, because the sum of its binary digits is even.

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

The square root of 21389807 is about 4624.9115667221. The cubic root of 21389807 is about 277.5890231924.

The spelling of 21389807 in words is "twenty-one million, three hundred eighty-nine thousand, eight hundred seven".