206196819921 has 27 divisors (see below), whose sum is σ = 311399752027. Its totient is φ = 131467847280.

The previous prime is 206196819887. The next prime is 206196819929. The reversal of 206196819921 is 129918691602.

The square root of 206196819921 is 454089.

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

206196819921 is a `hidden beast` number, since 2 + 0 + 619 + 6 + 8 + 19 + 9 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 49333296321 + 156863523600 = 222111^2 + 396060^2 .

It is not a de Polignac number, because 206196819921 - 2⁷ = 206196819793 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (206196819929) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 31328851 + ... + 31335431.

Almost surely, 2^206196819921 is an apocalyptic number.

206196819921 is the 454089-th square number.

206196819921 is the 227045-th centered octagonal number.

It is an amenable number.

206196819921 is a deficient number, since it is larger than the sum of its proper divisors (105202932106).

206196819921 is an frugal number, since it uses more digits than its factorization.

206196819921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13214 (or 6607 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 54.

The spelling of 206196819921 in words is "two hundred six billion, one hundred ninety-six million, eight hundred nineteen thousand, nine hundred twenty-one".