209769861 has 16 divisors (see below), whose sum is σ = 336473600. Its totient is φ = 113559408.

The previous prime is 209769853. The next prime is 209769863. The reversal of 209769861 is 168967902.

It is not a de Polignac number, because 209769861 - 2³ = 209769853 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 209769861.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209769863) 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 in 15 ways as a sum of consecutive naturals, for example, 262471 + ... + 263268.

It is an arithmetic number, because the mean of its divisors is an integer number (21029600).

Almost surely, 2^209769861 is an apocalyptic number.

209769861 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

209769861 is a deficient number, since it is larger than the sum of its proper divisors (126703739).

209769861 is a wasteful number, since it uses less digits than its factorization.

209769861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 525768.

The product of its (nonzero) digits is 326592, while the sum is 48.

The square root of 209769861 is about 14483.4340195963. The cubic root of 209769861 is about 594.1749844409.

The spelling of 209769861 in words is "two hundred nine million, seven hundred sixty-nine thousand, eight hundred sixty-one".