21428365 has 16 divisors (see below), whose sum is σ = 30183552. Its totient is φ = 14295744.

The previous prime is 21428339. The next prime is 21428383. The reversal of 21428365 is 56382412.

It is a cyclic number.

It is not a de Polignac number, because 21428365 - 2⁹ = 21427853 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6979 + ... + 9568.

It is an arithmetic number, because the mean of its divisors is an integer number (1886472).

Almost surely, 2^21428365 is an apocalyptic number.

It is an amenable number.

21428365 is a deficient number, since it is larger than the sum of its proper divisors (8755187).

21428365 is a wasteful number, since it uses less digits than its factorization.

21428365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16596.

The product of its digits is 11520, while the sum is 31.

The square root of 21428365 is about 4629.0782019750. The cubic root of 21428365 is about 277.7557202337.

The spelling of 21428365 in words is "twenty-one million, four hundred twenty-eight thousand, three hundred sixty-five".