21147195537664 has 243 divisors, whose sum is σ = 51847913147121. Its totient is φ = 8582106193920.

The previous prime is 21147195537647. The next prime is 21147195537749. The reversal of 21147195537664 is 46673559174112.

The square root of 21147195537664 is 4598608.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 13256939256064 + 7890256281600 = 3641008^2 + 2808960^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 9785836744 + ... + 9785838904.

Almost surely, 2^{21147195537664} is an apocalyptic number.

21147195537664 is the 4598608-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21147195537664

21147195537664 is an abundant number, since it is smaller than the sum of its proper divisors (30700717609457).

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

21147195537664 is an frugal number, since it uses more digits than its factorization.

21147195537664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4390 (or 2189 counting only the distinct ones).

The product of its digits is 38102400, while the sum is 61.

The spelling of 21147195537664 in words is "twenty-one trillion, one hundred forty-seven billion, one hundred ninety-five million, five hundred thirty-seven thousand, six hundred sixty-four".