206136221 has 4 divisors (see below), whose sum is σ = 207288000. Its totient is φ = 204984444.

The previous prime is 206136211. The next prime is 206136223. The reversal of 206136221 is 122631602.

206136221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 122631602 = 2 ⋅61315801.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-206136221 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (206136223) 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, 575621 + ... + 575978.

It is an arithmetic number, because the mean of its divisors is an integer number (51822000).

Almost surely, 2^206136221 is an apocalyptic number.

It is an amenable number.

206136221 is a deficient number, since it is larger than the sum of its proper divisors (1151779).

206136221 is a wasteful number, since it uses less digits than its factorization.

206136221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1151778.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 206136221 is about 14357.4447935557. Note that the first 3 decimals coincide. The cubic root of 206136221 is about 590.7242097969.

Adding to 206136221 its reverse (122631602), we get a palindrome (328767823).

The spelling of 206136221 in words is "two hundred six million, one hundred thirty-six thousand, two hundred twenty-one".