21090628 has 36 divisors (see below), whose sum is σ = 40780740. Its totient is φ = 9486720.

The previous prime is 21090583. The next prime is 21090631. The reversal of 21090628 is 82609012.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 8714304 + 12376324 = 2952^2 + 3518^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21090596 and 21090605.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 193438 + ... + 193546.

Almost surely, 2^21090628 is an apocalyptic number.

It is an amenable number.

21090628 is a deficient number, since it is larger than the sum of its proper divisors (19690112).

21090628 is a wasteful number, since it uses less digits than its factorization.

21090628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248 (or 185 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 21090628 is about 4592.4533748314. The cubic root of 21090628 is about 276.2887302631.

The spelling of 21090628 in words is "twenty-one million, ninety thousand, six hundred twenty-eight".