666820393 has 24 divisors (see below), whose sum is σ = 756664128. Its totient is φ = 586096896.

The previous prime is 666820373. The next prime is 666820397. The reversal of 666820393 is 393028666.

It is not a de Polignac number, because 666820393 - 2⁵ = 666820361 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666820397) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 284655 + ... + 286987.

It is an arithmetic number, because the mean of its divisors is an integer number (31527672).

Almost surely, 2^666820393 is an apocalyptic number.

It is an amenable number.

666820393 is a deficient number, since it is larger than the sum of its proper divisors (89843735).

666820393 is a wasteful number, since it uses less digits than its factorization.

666820393 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2433 (or 2416 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 43.

The square root of 666820393 is about 25822.8657007699. The cubic root of 666820393 is about 873.6476057368.

The spelling of 666820393 in words is "six hundred sixty-six million, eight hundred twenty thousand, three hundred ninety-three".