640400630 has 8 divisors (see below), whose sum is σ = 1152721152. Its totient is φ = 256160248.

The previous prime is 640400627. The next prime is 640400633. The reversal of 640400630 is 36004046.

It is an interprime number because it is at equal distance from previous prime (640400627) and next prime (640400633).

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×640400630² = 820225933808793800, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 640400596 and 640400605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640400633) 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, 32020022 + ... + 32020041.

It is an arithmetic number, because the mean of its divisors is an integer number (144090144).

Almost surely, 2^640400630 is an apocalyptic number.

640400630 is a deficient number, since it is larger than the sum of its proper divisors (512320522).

640400630 is a wasteful number, since it uses less digits than its factorization.

640400630 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64040070.

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 640400630 is about 25306.1381881946. The cubic root of 640400630 is about 861.9536574982.

Adding to 640400630 its reverse (36004046), we get a palindrome (676404676).

The spelling of 640400630 in words is "six hundred forty million, four hundred thousand, six hundred thirty".