649709281 has 12 divisors (see below), whose sum is σ = 743270332. Its totient is φ = 564450048.

The previous prime is 649709279. The next prime is 649709293. The reversal of 649709281 is 182907946.

It can be written as a sum of positive squares in 6 ways, for example, as 5564881 + 644144400 = 2359^2 + 25380^2 .

It is not a de Polignac number, because 649709281 - 2¹ = 649709279 is a prime.

It is a super-2 number, since 2×649709281² = 844244299635073922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649709261) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 82710 + ... + 90223.

Almost surely, 2^649709281 is an apocalyptic number.

It is an amenable number.

649709281 is a deficient number, since it is larger than the sum of its proper divisors (93561051).

649709281 is a wasteful number, since it uses less digits than its factorization.

649709281 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172980 (or 172963 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 46.

The square root of 649709281 is about 25489.3954616425. The cubic root of 649709281 is about 866.1099413816.

The spelling of 649709281 in words is "six hundred forty-nine million, seven hundred nine thousand, two hundred eighty-one".