21561230 has 8 divisors (see below), whose sum is σ = 38810232. Its totient is φ = 8624488.

The previous prime is 21561223. The next prime is 21561251. The reversal of 21561230 is 3216512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21561230² = 929773278225800, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1078052 + ... + 1078071.

It is an arithmetic number, because the mean of its divisors is an integer number (4851279).

Almost surely, 2^21561230 is an apocalyptic number.

21561230 is a deficient number, since it is larger than the sum of its proper divisors (17249002).

21561230 is a wasteful number, since it uses less digits than its factorization.

21561230 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2156130.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21561230 is about 4643.4071542349. The cubic root of 21561230 is about 278.3286057818.

Adding to 21561230 its reverse (3216512), we get a palindrome (24777742).

The spelling of 21561230 in words is "twenty-one million, five hundred sixty-one thousand, two hundred thirty".