649210921 has 2 divisors, whose sum is σ = 649210922. Its totient is φ = 649210920.

The previous prime is 649210901. The next prime is 649210937. The reversal of 649210921 is 129012946.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 636855696 + 12355225 = 25236^2 + 3515^2 .

It is a cyclic number.

It is not a de Polignac number, because 649210921 - 2²¹ = 647113769 is a prime.

It is not a weakly prime, because it can be changed into another prime (649210901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 324605460 + 324605461.

It is an arithmetic number, because the mean of its divisors is an integer number (324605461).

Almost surely, 2^649210921 is an apocalyptic number.

It is an amenable number.

649210921 is a deficient number, since it is larger than the sum of its proper divisors (1).

649210921 is an equidigital number, since it uses as much as digits as its factorization.

649210921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 649210921 is about 25479.6177561595. The cubic root of 649210921 is about 865.8884346391. Note that the first 3 decimals are identical.

The spelling of 649210921 in words is "six hundred forty-nine million, two hundred ten thousand, nine hundred twenty-one".