640710020 has 36 divisors (see below), whose sum is σ = 1420049484. Its totient is φ = 242792640.

The previous prime is 640710017. The next prime is 640710089. The reversal of 640710020 is 20017046.

It can be written as a sum of positive squares in 2 ways, for example, as 183006784 + 457703236 = 13528^2 + 21394^2 .

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 640709974 and 640710001.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37151 + ... + 51590.

It is an arithmetic number, because the mean of its divisors is an integer number (39445819).

Almost surely, 2^640710020 is an apocalyptic number.

It is an amenable number.

640710020 is an abundant number, since it is smaller than the sum of its proper divisors (779339464).

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

640710020 is a wasteful number, since it uses less digits than its factorization.

640710020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88788 (or 88767 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 640710020 is about 25312.2503938310. The cubic root of 640710020 is about 862.0924440094.

Adding to 640710020 its reverse (20017046), we get a palindrome (660727066).

The spelling of 640710020 in words is "six hundred forty million, seven hundred ten thousand, twenty".