649721505 has 16 divisors (see below), whose sum is σ = 1043313984. Its totient is φ = 345264960.

The previous prime is 649721489. The next prime is 649721507. The reversal of 649721505 is 505127946.

It is not a de Polignac number, because 649721505 - 2⁴ = 649721489 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (649721507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 74031 + ... + 82340.

It is an arithmetic number, because the mean of its divisors is an integer number (65207124).

Almost surely, 2^649721505 is an apocalyptic number.

It is an amenable number.

649721505 is a deficient number, since it is larger than the sum of its proper divisors (393592479).

649721505 is a wasteful number, since it uses less digits than its factorization.

649721505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156656.

The product of its (nonzero) digits is 75600, while the sum is 39.

The square root of 649721505 is about 25489.6352465075. The cubic root of 649721505 is about 866.1153731759.

The spelling of 649721505 in words is "six hundred forty-nine million, seven hundred twenty-one thousand, five hundred five".