205657990 has 8 divisors (see below), whose sum is σ = 370184400. Its totient is φ = 82263192.

The previous prime is 205657987. The next prime is 205658003. The reversal of 205657990 is 99756502.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 10282890 + ... + 10282909.

It is an arithmetic number, because the mean of its divisors is an integer number (46273050).

Almost surely, 2^205657990 is an apocalyptic number.

205657990 is a deficient number, since it is larger than the sum of its proper divisors (164526410).

205657990 is a wasteful number, since it uses less digits than its factorization.

205657990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20565806.

The product of its (nonzero) digits is 170100, while the sum is 43.

The square root of 205657990 is about 14340.7806621536. The cubic root of 205657990 is about 590.2670341541.

The spelling of 205657990 in words is "two hundred five million, six hundred fifty-seven thousand, nine hundred ninety".