206550021521 has 2 divisors, whose sum is σ = 206550021522. Its totient is φ = 206550021520.

The previous prime is 206550021499. The next prime is 206550021533. The reversal of 206550021521 is 125120055602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 142533431296 + 64016590225 = 377536^2 + 253015^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206550021521 is a prime.

It is a super-2 number, since 2×206550021521² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (206550021541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 103275010760 + 103275010761.

It is an arithmetic number, because the mean of its divisors is an integer number (103275010761).

Almost surely, 2^206550021521 is an apocalyptic number.

It is an amenable number.

206550021521 is a deficient number, since it is larger than the sum of its proper divisors (1).

206550021521 is an equidigital number, since it uses as much as digits as its factorization.

206550021521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6000, while the sum is 29.

The spelling of 206550021521 in words is "two hundred six billion, five hundred fifty million, twenty-one thousand, five hundred twenty-one".