21857630 has 16 divisors (see below), whose sum is σ = 39727584. Its totient is φ = 8657760.

The previous prime is 21857621. The next prime is 21857651. The reversal of 21857630 is 3675812.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 9581 + ... + 11640.

It is an arithmetic number, because the mean of its divisors is an integer number (2482974).

Almost surely, 2^21857630 is an apocalyptic number.

21857630 is a deficient number, since it is larger than the sum of its proper divisors (17869954).

21857630 is a wasteful number, since it uses less digits than its factorization.

21857630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21331.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21857630 is about 4675.2144335848. The cubic root of 21857630 is about 279.5981906729.

The spelling of 21857630 in words is "twenty-one million, eight hundred fifty-seven thousand, six hundred thirty".