651680640 has 320 divisors, whose sum is σ = 2508881760. Its totient is φ = 160247808.

The previous prime is 651680581. The next prime is 651680647. The reversal of 651680640 is 46086156.

651680640 is a `hidden beast` number, since 6 + 5 + 1 + 6 + 8 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (320).

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 651680595 and 651680604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (651680647) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 673437 + ... + 674403.

Almost surely, 2^651680640 is an apocalyptic number.

651680640 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 651680640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1254440880).

651680640 is an abundant number, since it is smaller than the sum of its proper divisors (1857201120).

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

651680640 is a wasteful number, since it uses less digits than its factorization.

651680640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1011 (or 990 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 36.

The square root of 651680640 is about 25528.0363522148. The cubic root of 651680640 is about 866.9850454192.

The spelling of 651680640 in words is "six hundred fifty-one million, six hundred eighty thousand, six hundred forty".