640987776 has 256 divisors, whose sum is σ = 2224252800. Its totient is φ = 179159040.

The previous prime is 640987747. The next prime is 640987793. The reversal of 640987776 is 677789046.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 493560 + ... + 494856.

Almost surely, 2^640987776 is an apocalyptic number.

640987776 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 640987776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1112126400).

640987776 is an abundant number, since it is smaller than the sum of its proper divisors (1583265024).

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

640987776 is a wasteful number, since it uses less digits than its factorization.

640987776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1344 (or 1326 counting only the distinct ones).

The product of its (nonzero) digits is 3556224, while the sum is 54.

The square root of 640987776 is about 25317.7363917077. The cubic root of 640987776 is about 862.2170020507.

The spelling of 640987776 in words is "six hundred forty million, nine hundred eighty-seven thousand, seven hundred seventy-six".