21505504530 has 32 divisors (see below), whose sum is σ = 52340162688. Its totient is φ = 5654028800.

The previous prime is 21505504529. The next prime is 21505504547. The reversal of 21505504530 is 3540550512.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5046111 + ... + 5050370.

It is an arithmetic number, because the mean of its divisors is an integer number (1635630084).

Almost surely, 2^21505504530 is an apocalyptic number.

21505504530 is an abundant number, since it is smaller than the sum of its proper divisors (30834658158).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21505504530 is a wasteful number, since it uses less digits than its factorization.

21505504530 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10096562.

The product of its (nonzero) digits is 15000, while the sum is 30.

The spelling of 21505504530 in words is "twenty-one billion, five hundred five million, five hundred four thousand, five hundred thirty".