205897821 has 4 divisors (see below), whose sum is σ = 274530432. Its totient is φ = 137265212.

The previous prime is 205897819. The next prime is 205897823. The reversal of 205897821 is 128798502.

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.

It is an interprime number because it is at equal distance from previous prime (205897819) and next prime (205897823).

It is a cyclic number.

It is not a de Polignac number, because 205897821 - 2¹ = 205897819 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205897823) 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, 34316301 + ... + 34316306.

It is an arithmetic number, because the mean of its divisors is an integer number (68632608).

Almost surely, 2^205897821 is an apocalyptic number.

It is an amenable number.

205897821 is a deficient number, since it is larger than the sum of its proper divisors (68632611).

205897821 is an equidigital number, since it uses as much as digits as its factorization.

205897821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 68632610.

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 205897821 is about 14349.1400787643. The cubic root of 205897821 is about 590.4963944618.

The spelling of 205897821 in words is "two hundred five million, eight hundred ninety-seven thousand, eight hundred twenty-one".