649691987 has 4 divisors (see below), whose sum is σ = 742505136. Its totient is φ = 556878840.

The previous prime is 649691983. The next prime is 649691989. The reversal of 649691987 is 789196946.

649691987 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 649691987 - 2² = 649691983 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (649691981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46406564 + ... + 46406577.

It is an arithmetic number, because the mean of its divisors is an integer number (185626284).

Almost surely, 2^649691987 is an apocalyptic number.

649691987 is a deficient number, since it is larger than the sum of its proper divisors (92813149).

649691987 is an equidigital number, since it uses as much as digits as its factorization.

649691987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92813148.

The product of its digits is 5878656, while the sum is 59.

The square root of 649691987 is about 25489.0562202683. The cubic root of 649691987 is about 866.1022565916.

The spelling of 649691987 in words is "six hundred forty-nine million, six hundred ninety-one thousand, nine hundred eighty-seven".