21389863 has 8 divisors (see below), whose sum is σ = 23371920. Its totient is φ = 19414080.

The previous prime is 21389857. The next prime is 21389869. The reversal of 21389863 is 36898312.

It is an interprime number because it is at equal distance from previous prime (21389857) and next prime (21389869).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21389863 - 2⁵ = 21389831 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21389869) 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 in 7 ways as a sum of consecutive naturals, for example, 8293 + ... + 10561.

It is an arithmetic number, because the mean of its divisors is an integer number (2921490).

Almost surely, 2^21389863 is an apocalyptic number.

21389863 is a deficient number, since it is larger than the sum of its proper divisors (1982057).

21389863 is a wasteful number, since it uses less digits than its factorization.

21389863 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3137.

The product of its digits is 62208, while the sum is 40.

The square root of 21389863 is about 4624.9176208880. The cubic root of 21389863 is about 277.5892654413.

The spelling of 21389863 in words is "twenty-one million, three hundred eighty-nine thousand, eight hundred sixty-three".