21388127 has 4 divisors (see below), whose sum is σ = 21398256. Its totient is φ = 21378000.

The previous prime is 21388117. The next prime is 21388139. The reversal of 21388127 is 72188312.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21388127 - 2²² = 17193823 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21388093 and 21388102.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21388117) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 563 + ... + 6564.

It is an arithmetic number, because the mean of its divisors is an integer number (5349564).

Almost surely, 2^21388127 is an apocalyptic number.

21388127 is a deficient number, since it is larger than the sum of its proper divisors (10129).

21388127 is an equidigital number, since it uses as much as digits as its factorization.

21388127 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10128.

The product of its digits is 5376, while the sum is 32.

The square root of 21388127 is about 4624.7299380612. The cubic root of 21388127 is about 277.5817555287.

The spelling of 21388127 in words is "twenty-one million, three hundred eighty-eight thousand, one hundred twenty-seven".