21621230 has 16 divisors (see below), whose sum is σ = 39070944. Its totient is φ = 8614560.

The previous prime is 21621181. The next prime is 21621233. The reversal of 21621230 is 3212612.

It is a junction number, because it is equal to n+sod(n) for n = 21621199 and 21621208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621233) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1481 + ... + 6740.

It is an arithmetic number, because the mean of its divisors is an integer number (2441934).

Almost surely, 2^21621230 is an apocalyptic number.

21621230 is a deficient number, since it is larger than the sum of its proper divisors (17449714).

21621230 is a wasteful number, since it uses less digits than its factorization.

21621230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8491.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21621230 is about 4649.8634388550. The cubic root of 21621230 is about 278.5865417429.

Adding to 21621230 its reverse (3212612), we get a palindrome (24833842).

The spelling of 21621230 in words is "twenty-one million, six hundred twenty-one thousand, two hundred thirty".