206356421 has 4 divisors (see below), whose sum is σ = 218495052. Its totient is φ = 194217792.

The previous prime is 206356417. The next prime is 206356439. The reversal of 206356421 is 124653602.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 125104225 + 81252196 = 11185^2 + 9014^2 .

It is not a de Polignac number, because 206356421 - 2² = 206356417 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206356411) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6069290 + ... + 6069323.

It is an arithmetic number, because the mean of its divisors is an integer number (54623763).

Almost surely, 2^206356421 is an apocalyptic number.

It is an amenable number.

206356421 is a deficient number, since it is larger than the sum of its proper divisors (12138631).

206356421 is a wasteful number, since it uses less digits than its factorization.

206356421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12138630.

The product of its (nonzero) digits is 8640, while the sum is 29.

The square root of 206356421 is about 14365.1112421728. Note that the first 3 decimals coincide. The cubic root of 206356421 is about 590.9344771959.

The spelling of 206356421 in words is "two hundred six million, three hundred fifty-six thousand, four hundred twenty-one".