209971641 has 32 divisors (see below), whose sum is σ = 340416000. Its totient is φ = 113460480.

The previous prime is 209971639. The next prime is 209971667. The reversal of 209971641 is 146179902.

It is not a de Polignac number, because 209971641 - 2¹ = 209971639 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 209971641.

It is not an unprimeable number, because it can be changed into a prime (209971241) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 810 + ... + 20508.

It is an arithmetic number, because the mean of its divisors is an integer number (10638000).

Almost surely, 2^209971641 is an apocalyptic number.

It is an amenable number.

209971641 is a deficient number, since it is larger than the sum of its proper divisors (130444359).

209971641 is a wasteful number, since it uses less digits than its factorization.

209971641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19749.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 209971641 is about 14490.3982346932. The cubic root of 209971641 is about 594.3654379317.

The spelling of 209971641 in words is "two hundred nine million, nine hundred seventy-one thousand, six hundred forty-one".