666241921 has 4 divisors (see below), whose sum is σ = 666328000. Its totient is φ = 666155844.

The previous prime is 666241909. The next prime is 666241949. The reversal of 666241921 is 129142666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 666241921 - 2⁵ = 666241889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666247921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30141 + ... + 47338.

It is an arithmetic number, because the mean of its divisors is an integer number (166582000).

Almost surely, 2^666241921 is an apocalyptic number.

It is an amenable number.

666241921 is a deficient number, since it is larger than the sum of its proper divisors (86079).

666241921 is an equidigital number, since it uses as much as digits as its factorization.

666241921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86078.

The product of its digits is 31104, while the sum is 37.

The square root of 666241921 is about 25811.6624997306. The cubic root of 666241921 is about 873.3949005635.

The spelling of 666241921 in words is "six hundred sixty-six million, two hundred forty-one thousand, nine hundred twenty-one".