646665739 has 2 divisors, whose sum is σ = 646665740. Its totient is φ = 646665738.

The previous prime is 646665727. The next prime is 646665847. The reversal of 646665739 is 937566646.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 646665739 - 2²³ = 638277131 is a prime.

It is a super-2 number, since 2×646665739² = 836353155992832242, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (646665139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323332869 + 323332870.

It is an arithmetic number, because the mean of its divisors is an integer number (323332870).

Almost surely, 2^646665739 is an apocalyptic number.

646665739 is a deficient number, since it is larger than the sum of its proper divisors (1).

646665739 is an equidigital number, since it uses as much as digits as its factorization.

646665739 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4898880, while the sum is 52.

The square root of 646665739 is about 25429.6232571385. The cubic root of 646665739 is about 864.7554027917.

The spelling of 646665739 in words is "six hundred forty-six million, six hundred sixty-five thousand, seven hundred thirty-nine".