666977409 has 56 divisors (see below), whose sum is σ = 1182538560. Its totient is φ = 367905888.

The previous prime is 666977407. The next prime is 666977417. The reversal of 666977409 is 904779666.

It is not a de Polignac number, because 666977409 - 2¹ = 666977407 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666977401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 145734 + ... + 150240.

It is an arithmetic number, because the mean of its divisors is an integer number (21116760).

Almost surely, 2^666977409 is an apocalyptic number.

It is an amenable number.

666977409 is a deficient number, since it is larger than the sum of its proper divisors (515561151).

666977409 is an equidigital number, since it uses as much as digits as its factorization.

666977409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4561 (or 4546 counting only the distinct ones).

The product of its (nonzero) digits is 3429216, while the sum is 54.

The square root of 666977409 is about 25825.9057730799. The cubic root of 666977409 is about 873.7161728693.

The spelling of 666977409 in words is "six hundred sixty-six million, nine hundred seventy-seven thousand, four hundred nine".