20680217521 has 16 divisors (see below), whose sum is σ = 22413104640. Its totient is φ = 19034547840.

The previous prime is 20680217497. The next prime is 20680217531. The reversal of 20680217521 is 12571208602.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20680217521 - 2¹⁵ = 20680184753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20680217531) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 111436 + ... + 231901.

It is an arithmetic number, because the mean of its divisors is an integer number (1400819040).

Almost surely, 2^20680217521 is an apocalyptic number.

It is an amenable number.

20680217521 is a deficient number, since it is larger than the sum of its proper divisors (1732887119).

20680217521 is a wasteful number, since it uses less digits than its factorization.

20680217521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343464.

The product of its (nonzero) digits is 13440, while the sum is 34.

The spelling of 20680217521 in words is "twenty billion, six hundred eighty million, two hundred seventeen thousand, five hundred twenty-one".