646402680 has 320 divisors, whose sum is σ = 2709780480. Its totient is φ = 134265600.

The previous prime is 646402661. The next prime is 646402697. The reversal of 646402680 is 86204646.

It is a happy number.

646402680 is a `hidden beast` number, since 6 + 4 + 640 + 2 + 6 + 8 + 0 = 666.

It is a super-2 number, since 2×646402680² = 835672849422364800, which contains 22 as substring.

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 congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 248185 + ... + 250775.

It is an arithmetic number, because the mean of its divisors is an integer number (8468064).

Almost surely, 2^646402680 is an apocalyptic number.

646402680 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 646402680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1354890240).

646402680 is an abundant number, since it is smaller than the sum of its proper divisors (2063377800).

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

646402680 is a wasteful number, since it uses less digits than its factorization.

646402680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2632 (or 2619 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 646402680 is about 25424.4504365384. The cubic root of 646402680 is about 864.6381281160.

The spelling of 646402680 in words is "six hundred forty-six million, four hundred two thousand, six hundred eighty".