646470720 has 420 divisors, whose sum is σ = 2680312140. Its totient is φ = 147474432.

The previous prime is 646470719. The next prime is 646470743. The reversal of 646470720 is 27074646.

646470720 is a `hidden beast` number, since 6 + 4 + 647 + 0 + 7 + 2 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 386358336 + 260112384 = 19656^2 + 16128^2 .

It is a tau number, because it is divible by the number of its divisors (420).

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

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 1269826 + ... + 1270334.

Almost surely, 2^646470720 is an apocalyptic number.

646470720 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 646470720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1340156070).

646470720 is an abundant number, since it is smaller than the sum of its proper divisors (2033841420).

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

646470720 is a wasteful number, since it uses less digits than its factorization.

646470720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552 (or 526 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 36.

The square root of 646470720 is about 25425.7884833489. The cubic root of 646470720 is about 864.6684641672.

The spelling of 646470720 in words is "six hundred forty-six million, four hundred seventy thousand, seven hundred twenty".