21620530 has 16 divisors (see below), whose sum is σ = 39866904. Its totient is φ = 8437120.

The previous prime is 21620513. The next prime is 21620531. The reversal of 21620530 is 3502612.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 8508889 + 13111641 = 2917^2 + 3621^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21620498 and 21620507.

It is not an unprimeable number, because it can be changed into a prime (21620531) 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 7 ways as a sum of consecutive naturals, for example, 25957 + ... + 26776.

Almost surely, 2^21620530 is an apocalyptic number.

21620530 is a deficient number, since it is larger than the sum of its proper divisors (18246374).

21620530 is a wasteful number, since it uses less digits than its factorization.

21620530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52781.

The product of its (nonzero) digits is 360, while the sum is 19.

The square root of 21620530 is about 4649.7881672179. The cubic root of 21620530 is about 278.5835352429.

The spelling of 21620530 in words is "twenty-one million, six hundred twenty thousand, five hundred thirty".