21551616450 has 144 divisors (see below), whose sum is σ = 71264147136. Its totient is φ = 4547145600.

The previous prime is 21551616413. The next prime is 21551616473. The reversal of 21551616450 is 5461615512.

21551616450 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 1 + 6 + 1 + 645 + 0 = 666.

It is a super-3 number, since 3×21551616450³ (a number of 32 digits) contains 333 as substring.

It is a Curzon number.

It is an unprimeable number.

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 71 ways as a sum of consecutive naturals, for example, 222196 + ... + 304095.

Almost surely, 2^21551616450 is an apocalyptic number.

21551616450 is an abundant number, since it is smaller than the sum of its proper divisors (49712530686).

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

21551616450 is a wasteful number, since it uses less digits than its factorization.

21551616450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526329 (or 526321 counting only the distinct ones).

The product of its (nonzero) digits is 36000, while the sum is 36.

The spelling of 21551616450 in words is "twenty-one billion, five hundred fifty-one million, six hundred sixteen thousand, four hundred fifty".