205621651 has 2 divisors, whose sum is σ = 205621652. Its totient is φ = 205621650.

The previous prime is 205621643. The next prime is 205621697. The reversal of 205621651 is 156126502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 205621651 - 2³ = 205621643 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (205621631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102810825 + 102810826.

It is an arithmetic number, because the mean of its divisors is an integer number (102810826).

Almost surely, 2^205621651 is an apocalyptic number.

205621651 is a deficient number, since it is larger than the sum of its proper divisors (1).

205621651 is an equidigital number, since it uses as much as digits as its factorization.

205621651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3600, while the sum is 28.

The square root of 205621651 is about 14339.5136249456. The cubic root of 205621651 is about 590.2322661116.

The spelling of 205621651 in words is "two hundred five million, six hundred twenty-one thousand, six hundred fifty-one".