21031628 has 6 divisors (see below), whose sum is σ = 36805356. Its totient is φ = 10515812.

The previous prime is 21031627. The next prime is 21031639. The reversal of 21031628 is 82613012.

It is not an unprimeable number, because it can be changed into a prime (21031627) 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 as a sum of consecutive naturals, namely, 2628950 + ... + 2628957.

It is an arithmetic number, because the mean of its divisors is an integer number (6134226).

Almost surely, 2^21031628 is an apocalyptic number.

It is an amenable number.

21031628 is a deficient number, since it is larger than the sum of its proper divisors (15773728).

21031628 is a wasteful number, since it uses less digits than its factorization.

21031628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5257911 (or 5257909 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21031628 is about 4586.0252943044. The cubic root of 21031628 is about 276.0308549136.

The spelling of 21031628 in words is "twenty-one million, thirty-one thousand, six hundred twenty-eight".