640698211 has 4 divisors (see below), whose sum is σ = 643918000. Its totient is φ = 637478424.

The previous prime is 640698199. The next prime is 640698217. The reversal of 640698211 is 112896046.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 640698211 - 2⁹ = 640697699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640698217) 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 in 3 ways as a sum of consecutive naturals, for example, 1609596 + ... + 1609993.

It is an arithmetic number, because the mean of its divisors is an integer number (160979500).

Almost surely, 2^640698211 is an apocalyptic number.

640698211 is a deficient number, since it is larger than the sum of its proper divisors (3219789).

640698211 is a wasteful number, since it uses less digits than its factorization.

640698211 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3219788.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 640698211 is about 25312.0171262584. The cubic root of 640698211 is about 862.0871475352.

The spelling of 640698211 in words is "six hundred forty million, six hundred ninety-eight thousand, two hundred eleven".