666822021 has 8 divisors (see below), whose sum is σ = 890613024. Its totient is φ = 443789520.

The previous prime is 666822017. The next prime is 666822031. The reversal of 666822021 is 120228666.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 666822021 - 2² = 666822017 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666822031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 187570 + ... + 191091.

It is an arithmetic number, because the mean of its divisors is an integer number (111326628).

Almost surely, 2^666822021 is an apocalyptic number.

It is an amenable number.

666822021 is a deficient number, since it is larger than the sum of its proper divisors (223791003).

666822021 is a wasteful number, since it uses less digits than its factorization.

666822021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 379251.

The product of its (nonzero) digits is 13824, while the sum is 33.

The square root of 666822021 is about 25822.8972232010. The cubic root of 666822021 is about 873.6483167214.

The spelling of 666822021 in words is "six hundred sixty-six million, eight hundred twenty-two thousand, twenty-one".