646611557 has 2 divisors, whose sum is σ = 646611558. Its totient is φ = 646611556.

The previous prime is 646611517. The next prime is 646611569. The reversal of 646611557 is 755116646.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 577488961 + 69122596 = 24031^2 + 8314^2 .

It is a cyclic number.

It is not a de Polignac number, because 646611557 - 2²² = 642417253 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646611517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323305778 + 323305779.

It is an arithmetic number, because the mean of its divisors is an integer number (323305779).

Almost surely, 2^646611557 is an apocalyptic number.

It is an amenable number.

646611557 is a deficient number, since it is larger than the sum of its proper divisors (1).

646611557 is an equidigital number, since it uses as much as digits as its factorization.

646611557 is an evil number, because the sum of its binary digits is even.

The product of its digits is 151200, while the sum is 41.

The square root of 646611557 is about 25428.5579024844. The cubic root of 646611557 is about 864.7312504448.

The spelling of 646611557 in words is "six hundred forty-six million, six hundred eleven thousand, five hundred fifty-seven".