21730628 has 24 divisors (see below), whose sum is σ = 40615680. Its totient is φ = 10150560.

The previous prime is 21730559. The next prime is 21730637. The reversal of 21730628 is 82603712.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a self number, because there is not a number n which added to its sum of digits gives 21730628.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 575 + ... + 6617.

It is an arithmetic number, because the mean of its divisors is an integer number (1692320).

Almost surely, 2^21730628 is an apocalyptic number.

It is an amenable number.

21730628 is a deficient number, since it is larger than the sum of its proper divisors (18885052).

21730628 is a wasteful number, since it uses less digits than its factorization.

21730628 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6107 (or 6105 counting only the distinct ones).

The product of its (nonzero) digits is 4032, while the sum is 29.

The square root of 21730628 is about 4661.6121674803. The cubic root of 21730628 is about 279.0556108450.

The spelling of 21730628 in words is "twenty-one million, seven hundred thirty thousand, six hundred twenty-eight".