646404977 has 2 divisors, whose sum is σ = 646404978. Its totient is φ = 646404976.

The previous prime is 646404943. The next prime is 646405007. The reversal of 646404977 is 779404646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 620557921 + 25847056 = 24911^2 + 5084^2 .

It is a cyclic number.

It is not a de Polignac number, because 646404977 - 2⁸ = 646404721 is a prime.

It is not a weakly prime, because it can be changed into another prime (646407977) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323202488 + 323202489.

It is an arithmetic number, because the mean of its divisors is an integer number (323202489).

Almost surely, 2^646404977 is an apocalyptic number.

It is an amenable number.

646404977 is a deficient number, since it is larger than the sum of its proper divisors (1).

646404977 is an equidigital number, since it uses as much as digits as its factorization.

646404977 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1016064, while the sum is 47.

The square root of 646404977 is about 25424.4956095495. The cubic root of 646404977 is about 864.6391522823.

The spelling of 646404977 in words is "six hundred forty-six million, four hundred four thousand, nine hundred seventy-seven".