651212640 has 288 divisors, whose sum is σ = 2451889440. Its totient is φ = 156377088.

The previous prime is 651212609. The next prime is 651212647. The reversal of 651212640 is 46212156.

651212640 is a `hidden beast` number, since 6 + 5 + 1 + 2 + 12 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (288).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (651212647) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 804556 + ... + 805364.

It is an arithmetic number, because the mean of its divisors is an integer number (8513505).

Almost surely, 2^651212640 is an apocalyptic number.

651212640 is a gapful number since it is divisible by the number (60) 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 651212640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1225944720).

651212640 is an abundant number, since it is smaller than the sum of its proper divisors (1800676800).

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

651212640 is a wasteful number, since it uses less digits than its factorization.

651212640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 886 (or 875 counting only the distinct ones).

The product of its (nonzero) digits is 2880, while the sum is 27.

The square root of 651212640 is about 25518.8683134656. The cubic root of 651212640 is about 866.7774559223. Note that the first 3 decimals are identical.

Adding to 651212640 its reverse (46212156), we get a palindrome (697424796).

The spelling of 651212640 in words is "six hundred fifty-one million, two hundred twelve thousand, six hundred forty".