666253621 has 8 divisors (see below), whose sum is σ = 731025504. Its totient is φ = 602182320.

The previous prime is 666253603. The next prime is 666253631. The reversal of 666253621 is 126352666.

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

It is a cyclic number.

It is not a de Polignac number, because 666253621 - 2⁷ = 666253493 is a prime.

It is a super-2 number, since 2×666253621² = 887787774991223282, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666253631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 173151 + ... + 176956.

It is an arithmetic number, because the mean of its divisors is an integer number (91378188).

Almost surely, 2^666253621 is an apocalyptic number.

It is an amenable number.

666253621 is a deficient number, since it is larger than the sum of its proper divisors (64771883).

666253621 is a wasteful number, since it uses less digits than its factorization.

666253621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 350291.

The product of its digits is 77760, while the sum is 37.

The square root of 666253621 is about 25811.8891404717. The cubic root of 666253621 is about 873.4000131511.

The spelling of 666253621 in words is "six hundred sixty-six million, two hundred fifty-three thousand, six hundred twenty-one".