209643990 has 16 divisors (see below), whose sum is σ = 503145648. Its totient is φ = 55905056.

The previous prime is 209643989. The next prime is 209644009. The reversal of 209643990 is 99346902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3494037 + ... + 3494096.

It is an arithmetic number, because the mean of its divisors is an integer number (31446603).

Almost surely, 2^209643990 is an apocalyptic number.

209643990 is an abundant number, since it is smaller than the sum of its proper divisors (293501658).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

209643990 is a wasteful number, since it uses less digits than its factorization.

209643990 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6988143.

The product of its (nonzero) digits is 104976, while the sum is 42.

The square root of 209643990 is about 14479.0880237672. The cubic root of 209643990 is about 594.0561170894.

The spelling of 209643990 in words is "two hundred nine million, six hundred forty-three thousand, nine hundred ninety".