209139819 has 16 divisors (see below), whose sum is σ = 318912768. Its totient is φ = 119424672.

The previous prime is 209139803. The next prime is 209139839. The reversal of 209139819 is 918931902.

It is not a de Polignac number, because 209139819 - 2⁴ = 209139803 is a prime.

It is a super-2 number, since 2×209139819² = 87478927782705522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (209139839) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39444 + ... + 44430.

It is an arithmetic number, because the mean of its divisors is an integer number (19932048).

Almost surely, 2^209139819 is an apocalyptic number.

209139819 is a deficient number, since it is larger than the sum of its proper divisors (109772949).

209139819 is a wasteful number, since it uses less digits than its factorization.

209139819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6994.

The product of its (nonzero) digits is 34992, while the sum is 42.

The square root of 209139819 is about 14461.6672275364. The cubic root of 209139819 is about 593.5795213760.

The spelling of 209139819 in words is "two hundred nine million, one hundred thirty-nine thousand, eight hundred nineteen".