646440493 has 2 divisors, whose sum is σ = 646440494. Its totient is φ = 646440492.

The previous prime is 646440433. The next prime is 646440503. The reversal of 646440493 is 394044646.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 646278084 + 162409 = 25422^2 + 403^2 .

It is a cyclic number.

It is not a de Polignac number, because 646440493 - 2²¹ = 644343341 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (646440433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 323220246 + 323220247.

It is an arithmetic number, because the mean of its divisors is an integer number (323220247).

Almost surely, 2^646440493 is an apocalyptic number.

It is an amenable number.

646440493 is a deficient number, since it is larger than the sum of its proper divisors (1).

646440493 is an equidigital number, since it uses as much as digits as its factorization.

646440493 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 248832, while the sum is 40.

The square root of 646440493 is about 25425.1940602230. The cubic root of 646440493 is about 864.6549875367.

The spelling of 646440493 in words is "six hundred forty-six million, four hundred forty thousand, four hundred ninety-three".