209861435388 has 72 divisors (see below), whose sum is σ = 538657592704. Its totient is φ = 63544995360.

The previous prime is 209861435383. The next prime is 209861435401. The reversal of 209861435388 is 883534168902.

It is a super-2 number, since 2×209861435388² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209861435383) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1836495 + ... + 1947417.

Almost surely, 2^209861435388 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209861435388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (269328796352).

209861435388 is an abundant number, since it is smaller than the sum of its proper divisors (328796157316).

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

209861435388 is a wasteful number, since it uses less digits than its factorization.

209861435388 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112255 (or 112242 counting only the distinct ones).

The product of its (nonzero) digits is 9953280, while the sum is 57.

The spelling of 209861435388 in words is "two hundred nine billion, eight hundred sixty-one million, four hundred thirty-five thousand, three hundred eighty-eight".