21530217178 has 16 divisors (see below), whose sum is σ = 33494877000. Its totient is φ = 10367167552.

The previous prime is 21530217173. The next prime is 21530217221. The reversal of 21530217178 is 87171203512.

It can be written as a sum of positive squares in 4 ways, for example, as 10423797409 + 11106419769 = 102097^2 + 105387^2 .

It is not an unprimeable number, because it can be changed into a prime (21530217173) 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, 454573 + ... + 499696.

Almost surely, 2^21530217178 is an apocalyptic number.

21530217178 is a deficient number, since it is larger than the sum of its proper divisors (11964659822).

21530217178 is a wasteful number, since it uses less digits than its factorization.

21530217178 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 954689.

The product of its (nonzero) digits is 23520, while the sum is 37.

The spelling of 21530217178 in words is "twenty-one billion, five hundred thirty million, two hundred seventeen thousand, one hundred seventy-eight".