20516922216521 has 16 divisors (see below), whose sum is σ = 20754037002240. Its totient is φ = 20280656407440.

The previous prime is 20516922216491. The next prime is 20516922216529. The reversal of 20516922216521 is 12561222961502.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20516922216521 - 2³⁰ = 20515848474697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20516922216529) 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, 806248220 + ... + 806273666.

It is an arithmetic number, because the mean of its divisors is an integer number (1297127312640).

Almost surely, 2^{20516922216521} is an apocalyptic number.

It is an amenable number.

20516922216521 is a deficient number, since it is larger than the sum of its proper divisors (237114785719).

20516922216521 is a wasteful number, since it uses less digits than its factorization.

20516922216521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41764.

The product of its (nonzero) digits is 259200, while the sum is 44.

The spelling of 20516922216521 in words is "twenty trillion, five hundred sixteen billion, nine hundred twenty-two million, two hundred sixteen thousand, five hundred twenty-one".