686867917840 has 40 divisors (see below), whose sum is σ = 1719811596888. Its totient is φ = 253612769280.

The previous prime is 686867917831. The next prime is 686867917867. The reversal of 686867917840 is 48719768686.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 139102145296 + 547765772544 = 372964^2 + 740112^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 686867917840.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 330223921 + ... + 330226000.

Almost surely, 2^686867917840 is an apocalyptic number.

It is an amenable number.

686867917840 is an abundant number, since it is smaller than the sum of its proper divisors (1032943679048).

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

686867917840 is a wasteful number, since it uses less digits than its factorization.

686867917840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660449947 (or 660449941 counting only the distinct ones).

The product of its (nonzero) digits is 195084288, while the sum is 70.

The spelling of 686867917840 in words is "six hundred eighty-six billion, eight hundred sixty-seven million, nine hundred seventeen thousand, eight hundred forty".