21368428 has 12 divisors (see below), whose sum is σ = 37518712. Its totient is φ = 10648800.

The previous prime is 21368401. The next prime is 21368429. The reversal of 21368428 is 82486312.

It is a junction number, because it is equal to n+sod(n) for n = 21368393 and 21368402.

It is not an unprimeable number, because it can be changed into a prime (21368429) 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 3 ways as a sum of consecutive naturals, for example, 7473 + ... + 9928.

Almost surely, 2^21368428 is an apocalyptic number.

It is an amenable number.

21368428 is a deficient number, since it is larger than the sum of its proper divisors (16150284).

21368428 is a wasteful number, since it uses less digits than its factorization.

21368428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17712 (or 17710 counting only the distinct ones).

The product of its digits is 18432, while the sum is 34.

The square root of 21368428 is about 4622.5997014667. The cubic root of 21368428 is about 277.4965094385.

It can be divided in two parts, 21 and 368428, that added together give a square (368449 = 607²).

The spelling of 21368428 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred twenty-eight".