209664690840 has 192 divisors, whose sum is σ = 768193423200. Its totient is φ = 50827772160.

The previous prime is 209664690799. The next prime is 209664690841. The reversal of 209664690840 is 48096466902.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (209664690841) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 671527 + ... + 932886.

Almost surely, 2^209664690840 is an apocalyptic number.

209664690840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

209664690840 is an abundant number, since it is smaller than the sum of its proper divisors (558528732360).

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

209664690840 is a wasteful number, since it uses less digits than its factorization.

209664690840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1604455 (or 1604434 counting only the distinct ones).

The product of its (nonzero) digits is 4478976, while the sum is 54.

The spelling of 209664690840 in words is "two hundred nine billion, six hundred sixty-four million, six hundred ninety thousand, eight hundred forty".