640662487 has 4 divisors (see below), whose sum is σ = 640868200. Its totient is φ = 640456776.

The previous prime is 640662481. The next prime is 640662541. The reversal of 640662487 is 784266046.

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 640662487 - 2²³ = 632273879 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640662481) 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, 98112 + ... + 104437.

It is an arithmetic number, because the mean of its divisors is an integer number (160217050).

Almost surely, 2^640662487 is an apocalyptic number.

640662487 is a deficient number, since it is larger than the sum of its proper divisors (205713).

640662487 is a wasteful number, since it uses less digits than its factorization.

640662487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205712.

The product of its (nonzero) digits is 387072, while the sum is 43.

The square root of 640662487 is about 25311.3114437004. The cubic root of 640662487 is about 862.0711245085.

The spelling of 640662487 in words is "six hundred forty million, six hundred sixty-two thousand, four hundred eighty-seven".