209678820648 has 64 divisors (see below), whose sum is σ = 572018673600. Its totient is φ = 63520442880.

The previous prime is 209678820647. The next prime is 209678820653. The reversal of 209678820648 is 846028876902.

It is a Cunningham number, because it is equal to 457907²-1.

It is a super-2 number, since 2×209678820648² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 209678820591 and 209678820600.

It is not an unprimeable number, because it can be changed into a prime (209678820647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 801340 + ... + 1030292.

It is an arithmetic number, because the mean of its divisors is an integer number (8937791775).

Almost surely, 2^209678820648 is an apocalyptic number.

It is an amenable number.

209678820648 is an abundant number, since it is smaller than the sum of its proper divisors (362339852952).

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

209678820648 is a wasteful number, since it uses less digits than its factorization.

209678820648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232442 (or 232438 counting only the distinct ones).

The product of its (nonzero) digits is 18579456, while the sum is 60.

The spelling of 209678820648 in words is "two hundred nine billion, six hundred seventy-eight million, eight hundred twenty thousand, six hundred forty-eight".