209740128 has 96 divisors (see below), whose sum is σ = 618782976. Its totient is φ = 61721088.

The previous prime is 209740127. The next prime is 209740129. The reversal of 209740128 is 821047902.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (209740127) and next prime (209740129).

It is a tau number, because it is divible by the number of its divisors (96).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209740121) 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, 25051 + ... + 32357.

It is an arithmetic number, because the mean of its divisors is an integer number (6445656).

Almost surely, 2^209740128 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 209740128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (309391488).

209740128 is an abundant number, since it is smaller than the sum of its proper divisors (409042848).

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

209740128 is a wasteful number, since it uses less digits than its factorization.

209740128 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7356 (or 7348 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 209740128 is about 14482.4075346608. The cubic root of 209740128 is about 594.1469101194.

The spelling of 209740128 in words is "two hundred nine million, seven hundred forty thousand, one hundred twenty-eight".