209872869 has 4 divisors (see below), whose sum is σ = 279830496. Its totient is φ = 139915244.

The previous prime is 209872847. The next prime is 209872889. The reversal of 209872869 is 968278902.

It is a happy number.

209872869 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 a cyclic number.

It is not a de Polignac number, because 209872869 - 2⁹ = 209872357 is a prime.

It is a super-2 number, since 2×209872869² = 88093242284582322, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209872829) 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, 34978809 + ... + 34978814.

It is an arithmetic number, because the mean of its divisors is an integer number (69957624).

Almost surely, 2^209872869 is an apocalyptic number.

It is an amenable number.

209872869 is a deficient number, since it is larger than the sum of its proper divisors (69957627).

209872869 is an equidigital number, since it uses as much as digits as its factorization.

209872869 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 69957626.

The product of its (nonzero) digits is 870912, while the sum is 51.

The square root of 209872869 is about 14486.9896458857. The cubic root of 209872869 is about 594.2722255492.

The spelling of 209872869 in words is "two hundred nine million, eight hundred seventy-two thousand, eight hundred sixty-nine".