209149640 has 96 divisors (see below), whose sum is σ = 579710520. Its totient is φ = 67479552.

The previous prime is 209149621. The next prime is 209149667. The reversal of 209149640 is 46941902.

It can be written as a sum of positive squares in 4 ways, for example, as 209149444 + 196 = 14462^2 + 14^2 .

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a self number, because there is not a number n which added to its sum of digits gives 209149640.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30182 + ... + 36458.

Almost surely, 2^209149640 is an apocalyptic number.

209149640 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 209149640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (289855260).

209149640 is an abundant number, since it is smaller than the sum of its proper divisors (370560880).

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

209149640 is a wasteful number, since it uses less digits than its factorization.

209149640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6319 (or 6308 counting only the distinct ones).

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 209149640 is about 14462.0067763779. The cubic root of 209149640 is about 593.5888125339.

The spelling of 209149640 in words is "two hundred nine million, one hundred forty-nine thousand, six hundred forty".