21630686 has 36 divisors (see below), whose sum is σ = 41122536. Its totient is φ = 8352960.

The previous prime is 21630659. The next prime is 21630689. The reversal of 21630686 is 68603612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21630689) 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 in 17 ways as a sum of consecutive naturals, for example, 191366 + ... + 191478.

Almost surely, 2^21630686 is an apocalyptic number.

21630686 is a deficient number, since it is larger than the sum of its proper divisors (19491850).

21630686 is a wasteful number, since it uses less digits than its factorization.

21630686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257 (or 133 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 32.

The square root of 21630686 is about 4650.8801317600. The cubic root of 21630686 is about 278.6271489053.

The spelling of 21630686 in words is "twenty-one million, six hundred thirty thousand, six hundred eighty-six".