209387940 has 48 divisors (see below), whose sum is σ = 589825152. Its totient is φ = 55499776.

The previous prime is 209387939. The next prime is 209387947. The reversal of 209387940 is 49783902.

It is a junction number, because it is equal to n+sod(n) for n = 209387892 and 209387901.

It is not an unprimeable number, because it can be changed into a prime (209387947) 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, 429 + ... + 20468.

It is an arithmetic number, because the mean of its divisors is an integer number (12288024).

Almost surely, 2^209387940 is an apocalyptic number.

209387940 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 209387940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (294912576).

209387940 is an abundant number, since it is smaller than the sum of its proper divisors (380437212).

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

209387940 is a wasteful number, since it uses less digits than its factorization.

209387940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21076 (or 21074 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 42.

The square root of 209387940 is about 14470.2432598765. The cubic root of 209387940 is about 593.8141671741.

The spelling of 209387940 in words is "two hundred nine million, three hundred eighty-seven thousand, nine hundred forty".