21018628 has 12 divisors (see below), whose sum is σ = 36832320. Its totient is φ = 10495112.

The previous prime is 21018623. The next prime is 21018631. The reversal of 21018628 is 82681012.

It is a junction number, because it is equal to n+sod(n) for n = 21018596 and 21018605.

It is not an unprimeable number, because it can be changed into a prime (21018623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 225 + ... + 6487.

It is an arithmetic number, because the mean of its divisors is an integer number (3069360).

Almost surely, 2^21018628 is an apocalyptic number.

It is an amenable number.

21018628 is a deficient number, since it is larger than the sum of its proper divisors (15813692).

21018628 is a wasteful number, since it uses less digits than its factorization.

21018628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7106 (or 7104 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 21018628 is about 4584.6077258583. The cubic root of 21018628 is about 275.9739701000.

The spelling of 21018628 in words is "twenty-one million, eighteen thousand, six hundred twenty-eight".