21521220530 has 16 divisors (see below), whose sum is σ = 38742461784. Its totient is φ = 8607540480.

The previous prime is 21521220521. The next prime is 21521220571. The reversal of 21521220530 is 3502212512.

It can be written as a sum of positive squares in 4 ways, for example, as 16886742601 + 4634477929 = 129949^2 + 68077^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21521220496 and 21521220505.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19127 + ... + 208346.

Almost surely, 2^21521220530 is an apocalyptic number.

21521220530 is a deficient number, since it is larger than the sum of its proper divisors (17221241254).

21521220530 is a wasteful number, since it uses less digits than its factorization.

21521220530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 236941.

The product of its (nonzero) digits is 1200, while the sum is 23.

The spelling of 21521220530 in words is "twenty-one billion, five hundred twenty-one million, two hundred twenty thousand, five hundred thirty".