20754785521 has 8 divisors (see below), whose sum is σ = 21263523624. Its totient is φ = 20246167680.

The previous prime is 20754785509. The next prime is 20754785567. The reversal of 20754785521 is 12558745702.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 438274225 + 20316511296 = 20935^2 + 142536^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 20754785521 - 2²⁹ = 20217914609 is a prime.

It is a super-2 number, since 2×20754785521² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20754785591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 390475 + ... + 440431.

It is an arithmetic number, because the mean of its divisors is an integer number (2657940453).

Almost surely, 2^20754785521 is an apocalyptic number.

It is an amenable number.

20754785521 is a deficient number, since it is larger than the sum of its proper divisors (508738103).

20754785521 is a wasteful number, since it uses less digits than its factorization.

20754785521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60131.

The product of its (nonzero) digits is 784000, while the sum is 46.

The spelling of 20754785521 in words is "twenty billion, seven hundred fifty-four million, seven hundred eighty-five thousand, five hundred twenty-one".