640987515 has 48 divisors (see below), whose sum is σ = 1336608000. Its totient is φ = 277598016.

The previous prime is 640987507. The next prime is 640987559. The reversal of 640987515 is 515789046.

640987515 is a `hidden beast` number, since 6 + 40 + 98 + 7 + 515 = 666.

It is not a de Polignac number, because 640987515 - 2³ = 640987507 is a prime.

It is a super-3 number, since 3×640987515³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 47565 + ... + 59534.

It is an arithmetic number, because the mean of its divisors is an integer number (27846000).

Almost surely, 2^640987515 is an apocalyptic number.

640987515 is an abundant number, since it is smaller than the sum of its proper divisors (695620485).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

640987515 is a wasteful number, since it uses less digits than its factorization.

640987515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107136 (or 107133 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The square root of 640987515 is about 25317.7312372179. The cubic root of 640987515 is about 862.2168850237.

The spelling of 640987515 in words is "six hundred forty million, nine hundred eighty-seven thousand, five hundred fifteen".