666387643 has 2 divisors, whose sum is σ = 666387644. Its totient is φ = 666387642.

The previous prime is 666387593. The next prime is 666387677. The reversal of 666387643 is 346783666.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666387643 - 2¹³ = 666379451 is a prime.

It is not a weakly prime, because it can be changed into another prime (666387343) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333193821 + 333193822.

It is an arithmetic number, because the mean of its divisors is an integer number (333193822).

Almost surely, 2^666387643 is an apocalyptic number.

666387643 is a deficient number, since it is larger than the sum of its proper divisors (1).

666387643 is an equidigital number, since it uses as much as digits as its factorization.

666387643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2612736, while the sum is 49.

The square root of 666387643 is about 25814.4851391617. The cubic root of 666387643 is about 873.4585729172.

The spelling of 666387643 in words is "six hundred sixty-six million, three hundred eighty-seven thousand, six hundred forty-three".