668999861 has 16 divisors (see below), whose sum is σ = 753053760. Its totient is φ = 590572800.

The previous prime is 668999797. The next prime is 668999893. The reversal of 668999861 is 168999866.

It is a cyclic number.

It is not a de Polignac number, because 668999861 - 2⁶ = 668999797 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 668999794 and 668999803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668299861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22370 + ... + 42876.

It is an arithmetic number, because the mean of its divisors is an integer number (47065860).

Almost surely, 2^668999861 is an apocalyptic number.

It is an amenable number.

668999861 is a deficient number, since it is larger than the sum of its proper divisors (84053899).

668999861 is a wasteful number, since it uses less digits than its factorization.

668999861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20644.

The product of its digits is 10077696, while the sum is 62.

The square root of 668999861 is about 25865.0316257297. The cubic root of 668999861 is about 874.5983946391.

The spelling of 668999861 in words is "six hundred sixty-eight million, nine hundred ninety-nine thousand, eight hundred sixty-one".