21030638 has 4 divisors (see below), whose sum is σ = 31545960. Its totient is φ = 10515318.

The previous prime is 21030637. The next prime is 21030677. The reversal of 21030638 is 83603012.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21030637) by changing a digit.

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 as a sum of consecutive naturals, namely, 5257658 + ... + 5257661.

It is an arithmetic number, because the mean of its divisors is an integer number (7886490).

Almost surely, 2^21030638 is an apocalyptic number.

21030638 is a deficient number, since it is larger than the sum of its proper divisors (10515322).

21030638 is a wasteful number, since it uses less digits than its factorization.

21030638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10515321.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21030638 is about 4585.9173564294. The cubic root of 21030638 is about 276.0265237410.

The spelling of 21030638 in words is "twenty-one million, thirty thousand, six hundred thirty-eight".